我收到此错误：
java.lang.Exception: java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, received org.apache.hadoop.io.LongWritable
at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.io.IOException: Type mismatch in key from map: expected org.apache.hadoop.io.Text, received org.apache.hadoop.io.LongWritable
at org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:1074)
at org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:715)
at org.apache.hadoop.mapreduce.task.TaskInputOutputContextImpl.write(TaskInputOutputContextImpl.java:89)
at org.apache.hadoop.mapreduce.lib.map.WrappedMapper$Context.write(WrappedMapper.java:112)
at org.apache.hadoop.mapreduce.Mapper.map(Mapper.java:125)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
来自此代码：
public class MyAvroApplication {
private static class MyReducer extends Reducer<Email, Text, Text, Text> {
private Text from = new Text();
private Text subject = new Text();
public void reduce(Email key, Iterable<Text> values, Context context)
throws IOException, InterruptedException {
from.set(key.getFrom().toString());
subject.set(key.getSubject().toString());
context.write(from, subject);
}
}
private static class MyAvroMapper extends Mapper<Text, Email, Email, Text> {
protected void map(Email email, NullWritable value, Context context) throws IOException, InterruptedException {
context.write(email,
new Text(email.getSubject().toString()));
}
}
public static void main(String[] args) throws Exception {
UserGroupInformation ugi = UserGroupInformation.createRemoteUser("hdfs");
ugi.doAs(new PrivilegedExceptionAction<Void>() {
public Void run() throws Exception {
Configuration conf = new Configuration();
conf.set("fs.defaultFS", "hdfs://127.0.0.1:8020/user/rich");
conf.set("hadoop.job.ugi", "hdfs");
Job job = Job.getInstance(conf, "mytest");
AvroJob.setInputKeySchema(job, Email.getClassSchema());
AvroJob.setOutputKeySchema(job, Email.getClassSchema());
job.setJarByClass(MyApplication.class);
job.setMapperClass(MyAvroMapper.class);
job.setCombinerClass(MyReducer.class);
job.setReducerClass(MyReducer.class);
// job.setInputFormatClass(AvroKeyInputFormat.class);
// job.setOutputFormatClass(AvroKeyOutputFormat.class);
job.setOutputKeyClass(Text.class);
job.setOutputValueClass(Text.class);
FileInputFormat.addInputPath(job, new Path("/user/rich/in/"));
FileOutputFormat.setOutputPath(job, new Path("/user/rich/out/"));
boolean result = job.waitForCompletion(true);
System.out.println(result);
return null;
}
});
}
}
我真的很难理解如何在进出的路上匹配各种键值参数。我的目的是以电子邮件的形式阅读一些Avro格式文件，然后运行一些简单的计算，只计算电子邮件的数量将是一个良好的开端。
编辑：
此Mapper出现类似错误：
private static class MyAvroMapper extends Mapper<Text, AvroKey<Email>, AvroKey<Email>, Text> {
protected void map(Text key, AvroKey<Email> email, Context context) throws IOException, InterruptedException {
context.write(email,
new Text(email.datum().getSubject().toString()));
}
}
错误：
java.lang.Exception: java.lang.ClassCastException: org.apache.hadoop.io.LongWritable cannot be cast to org.apache.hadoop.io.Text
at org.apache.hadoop.mapred.LocalJobRunner$Job.runTasks(LocalJobRunner.java:462)
at org.apache.hadoop.mapred.LocalJobRunner$Job.run(LocalJobRunner.java:522)
Caused by: java.lang.ClassCastException: org.apache.hadoop.io.LongWritable cannot be cast to org.apache.hadoop.io.Text
at com.test.myapp.MyAvroApplication$MyAvroMapper.map(MyAvroApplication.java:1)
at org.apache.hadoop.mapreduce.Mapper.run(Mapper.java:146)
at org.apache.hadoop.mapred.MapTask.runNewMapper(MapTask.java:787)
at org.apache.hadoop.mapred.MapTask.run(MapTask.java:341)
at org.apache.hadoop.mapred.LocalJobRunner$Job$MapTaskRunnable.run(LocalJobRunner.java:243)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
从架构生成的电子邮件类：
@SuppressWarnings("all")
@org.apache.avro.specific.AvroGenerated
public class Email extends org.apache.avro.specific.SpecificRecordBase implements org.apache.avro.specific.SpecificRecord {
public static final org.apache.avro.Schema SCHEMA$ = new org.apache.avro.Schema.Parser().parse("{\"type\":\"record\",\"name\":\"Email\",\"namespace\":\"com.test.myapp.avro\",\"fields\":[{\"name\":\"message_id\",\"type\":[\"null\",\"string\"],\"doc\":\"\"},{\"name\":\"date\",\"type\":[\"long\",\"null\"]},{\"name\":\"from\",\"type\":{\"type\":\"record\",\"name\":\"EmailAddress\",\"fields\":[{\"name\":\"name\",\"type\":[\"null\",\"string\"],\"doc\":\"\"},{\"name\":\"address\",\"type\":[\"null\",\"string\"],\"doc\":\"\"}]}},{\"name\":\"subject\",\"type\":[\"string\",\"null\"]},{\"name\":\"body\",\"type\":[\"string\",\"null\"]},{\"name\":\"tos\",\"type\":[\"null\",{\"type\":\"array\",\"items\":[\"null\",\"EmailAddress\"]}],\"doc\":\"\"},{\"name\":\"ccs\",\"type\":[\"null\",{\"type\":\"array\",\"items\":[\"null\",\"EmailAddress\"]}],\"doc\":\"\"},{\"name\":\"bccs\",\"type\":[\"null\",{\"type\":\"array\",\"items\":[\"null\",\"EmailAddress\"]}],\"doc\":\"\"}]}");
public static org.apache.avro.Schema getClassSchema() { return SCHEMA$; }
/** */
@Deprecated public java.lang.CharSequence message_id;
@Deprecated public java.lang.Long date;
@Deprecated public com.test.myapp.avro.EmailAddress from;
@Deprecated public java.lang.CharSequence subject;
@Deprecated public java.lang.CharSequence body;
/** */
@Deprecated public java.util.List<com.test.myapp.avro.EmailAddress> tos;
/** */
@Deprecated public java.util.List<com.test.myapp.avro.EmailAddress> ccs;
/** */
@Deprecated public java.util.List<com.test.myapp.avro.EmailAddress> bccs;
/**
* Default constructor. Note that this does not initialize fields
* to their default values from the schema. If that is desired then
* one should use <code>newBuilder()</code>.
*/
public Email() {}
/**
* All-args constructor.
*/
public Email(java.lang.CharSequence message_id, java.lang.Long date, com.test.myapp.avro.EmailAddress from, java.lang.CharSequence subject, java.lang.CharSequence body, java.util.List<com.test.myapp.avro.EmailAddress> tos, java.util.List<com.test.myapp.avro.EmailAddress> ccs, java.util.List<com.test.myapp.avro.EmailAddress> bccs) {
this.message_id = message_id;
this.date = date;
this.from = from;
this.subject = subject;
this.body = body;
this.tos = tos;
this.ccs = ccs;
this.bccs = bccs;
}
public org.apache.avro.Schema getSchema() { return SCHEMA$; }
// Used by DatumWriter. Applications should not call.
public java.lang.Object get(int field$) {
switch (field$) {
case 0: return message_id;
case 1: return date;
case 2: return from;
case 3: return subject;
case 4: return body;
case 5: return tos;
case 6: return ccs;
case 7: return bccs;
default: throw new org.apache.avro.AvroRuntimeException("Bad index");
}
}
// Used by DatumReader. Applications should not call.
@SuppressWarnings(value="unchecked")
public void put(int field$, java.lang.Object value$) {
switch (field$) {
case 0: message_id = (java.lang.CharSequence)value$; break;
case 1: date = (java.lang.Long)value$; break;
case 2: from = (com.test.myapp.avro.EmailAddress)value$; break;
case 3: subject = (java.lang.CharSequence)value$; break;
case 4: body = (java.lang.CharSequence)value$; break;
case 5: tos = (java.util.List<com.test.myapp.avro.EmailAddress>)value$; break;
case 6: ccs = (java.util.List<com.test.myapp.avro.EmailAddress>)value$; break;
case 7: bccs = (java.util.List<com.test.myapp.avro.EmailAddress>)value$; break;
default: throw new org.apache.avro.AvroRuntimeException("Bad index");
}
}
/**
* Gets the value of the 'message_id' field.
* */
public java.lang.CharSequence getMessageId() {
return message_id;
}
/**
* Sets the value of the 'message_id' field.
* * @param value the value to set.
*/
public void setMessageId(java.lang.CharSequence value) {
this.message_id = value;
}
/**
* Gets the value of the 'date' field.
*/
public java.lang.Long getDate() {
return date;
}
/**
* Sets the value of the 'date' field.
* @param value the value to set.
*/
public void setDate(java.lang.Long value) {
this.date = value;
}
/**
* Gets the value of the 'from' field.
*/
public com.test.myapp.avro.EmailAddress getFrom() {
return from;
}
/**
* Sets the value of the 'from' field.
* @param value the value to set.
*/
public void setFrom(com.test.myapp.avro.EmailAddress value) {
this.from = value;
}
/**
* Gets the value of the 'subject' field.
*/
public java.lang.CharSequence getSubject() {
return subject;
}
/**
* Sets the value of the 'subject' field.
* @param value the value to set.
*/
public void setSubject(java.lang.CharSequence value) {
this.subject = value;
}
/**
* Gets the value of the 'body' field.
*/
public java.lang.CharSequence getBody() {
return body;
}
/**
* Sets the value of the 'body' field.
* @param value the value to set.
*/
public void setBody(java.lang.CharSequence value) {
this.body = value;
}
/**
* Gets the value of the 'tos' field.
* */
public java.util.List<com.test.myapp.avro.EmailAddress> getTos() {
return tos;
}
/**
* Sets the value of the 'tos' field.
* * @param value the value to set.
*/
public void setTos(java.util.List<com.test.myapp.avro.EmailAddress> value) {
this.tos = value;
}
/**
* Gets the value of the 'ccs' field.
* */
public java.util.List<com.test.myapp.avro.EmailAddress> getCcs() {
return ccs;
}
/**
* Sets the value of the 'ccs' field.
* * @param value the value to set.
*/
public void setCcs(java.util.List<com.test.myapp.avro.EmailAddress> value) {
this.ccs = value;
}
/**
* Gets the value of the 'bccs' field.
* */
public java.util.List<com.test.myapp.avro.EmailAddress> getBccs() {
return bccs;
}
/**
* Sets the value of the 'bccs' field.
* * @param value the value to set.
*/
public void setBccs(java.util.List<com.test.myapp.avro.EmailAddress> value) {
this.bccs = value;
}
/** Creates a new Email RecordBuilder */
public static com.test.myapp.avro.Email.Builder newBuilder() {
return new com.test.myapp.avro.Email.Builder();
}
/** Creates a new Email RecordBuilder by copying an existing Builder */
public static com.test.myapp.avro.Email.Builder newBuilder(com.test.myapp.avro.Email.Builder other) {
return new com.test.myapp.avro.Email.Builder(other);
}
/** Creates a new Email RecordBuilder by copying an existing Email instance */
public static com.test.myapp.avro.Email.Builder newBuilder(com.test.myapp.avro.Email other) {
return new com.test.myapp.avro.Email.Builder(other);
}
/**
* RecordBuilder for Email instances.
*/
public static class Builder extends org.apache.avro.specific.SpecificRecordBuilderBase<Email>
implements org.apache.avro.data.RecordBuilder<Email> {
private java.lang.CharSequence message_id;
private java.lang.Long date;
private com.test.myapp.avro.EmailAddress from;
private java.lang.CharSequence subject;
private java.lang.CharSequence body;
private java.util.List<com.test.myapp.avro.EmailAddress> tos;
private java.util.List<com.test.myapp.avro.EmailAddress> ccs;
private java.util.List<com.test.myapp.avro.EmailAddress> bccs;
/** Creates a new Builder */
private Builder() {
super(com.test.myapp.avro.Email.SCHEMA$);
}
/** Creates a Builder by copying an existing Builder */
private Builder(com.test.myapp.avro.Email.Builder other) {
super(other);
if (isValidValue(fields()[0], other.message_id)) {
this.message_id = data().deepCopy(fields()[0].schema(), other.message_id);
fieldSetFlags()[0] = true;
}
if (isValidValue(fields()[1], other.date)) {
this.date = data().deepCopy(fields()[1].schema(), other.date);
fieldSetFlags()[1] = true;
}
if (isValidValue(fields()[2], other.from)) {
this.from = data().deepCopy(fields()[2].schema(), other.from);
fieldSetFlags()[2] = true;
}
if (isValidValue(fields()[3], other.subject)) {
this.subject = data().deepCopy(fields()[3].schema(), other.subject);
fieldSetFlags()[3] = true;
}
if (isValidValue(fields()[4], other.body)) {
this.body = data().deepCopy(fields()[4].schema(), other.body);
fieldSetFlags()[4] = true;
}
if (isValidValue(fields()[5], other.tos)) {
this.tos = data().deepCopy(fields()[5].schema(), other.tos);
fieldSetFlags()[5] = true;
}
if (isValidValue(fields()[6], other.ccs)) {
this.ccs = data().deepCopy(fields()[6].schema(), other.ccs);
fieldSetFlags()[6] = true;
}
if (isValidValue(fields()[7], other.bccs)) {
this.bccs = data().deepCopy(fields()[7].schema(), other.bccs);
fieldSetFlags()[7] = true;
}
}
/** Creates a Builder by copying an existing Email instance */
private Builder(com.test.myapp.avro.Email other) {
super(com.test.myapp.avro.Email.SCHEMA$);
if (isValidValue(fields()[0], other.message_id)) {
this.message_id = data().deepCopy(fields()[0].schema(), other.message_id);
fieldSetFlags()[0] = true;
}
if (isValidValue(fields()[1], other.date)) {
this.date = data().deepCopy(fields()[1].schema(), other.date);
fieldSetFlags()[1] = true;
}
if (isValidValue(fields()[2], other.from)) {
this.from = data().deepCopy(fields()[2].schema(), other.from);
fieldSetFlags()[2] = true;
}
if (isValidValue(fields()[3], other.subject)) {
this.subject = data().deepCopy(fields()[3].schema(), other.subject);
fieldSetFlags()[3] = true;
}
if (isValidValue(fields()[4], other.body)) {
this.body = data().deepCopy(fields()[4].schema(), other.body);
fieldSetFlags()[4] = true;
}
if (isValidValue(fields()[5], other.tos)) {
this.tos = data().deepCopy(fields()[5].schema(), other.tos);
fieldSetFlags()[5] = true;
}
if (isValidValue(fields()[6], other.ccs)) {
this.ccs = data().deepCopy(fields()[6].schema(), other.ccs);
fieldSetFlags()[6] = true;
}
if (isValidValue(fields()[7], other.bccs)) {
this.bccs = data().deepCopy(fields()[7].schema(), other.bccs);
fieldSetFlags()[7] = true;
}
}
/** Gets the value of the 'message_id' field */
public java.lang.CharSequence getMessageId() {
return message_id;
}
/** Sets the value of the 'message_id' field */
public com.test.myapp.avro.Email.Builder setMessageId(java.lang.CharSequence value) {
validate(fields()[0], value);
this.message_id = value;
fieldSetFlags()[0] = true;
return this;
}
/** Checks whether the 'message_id' field has been set */
public boolean hasMessageId() {
return fieldSetFlags()[0];
}
/** Clears the value of the 'message_id' field */
public com.test.myapp.avro.Email.Builder clearMessageId() {
message_id = null;
fieldSetFlags()[0] = false;
return this;
}
/** Gets the value of the 'date' field */
public java.lang.Long getDate() {
return date;
}
/** Sets the value of the 'date' field */
public com.test.myapp.avro.Email.Builder setDate(java.lang.Long value) {
validate(fields()[1], value);
this.date = value;
fieldSetFlags()[1] = true;
return this;
}
/** Checks whether the 'date' field has been set */
public boolean hasDate() {
return fieldSetFlags()[1];
}
/** Clears the value of the 'date' field */
public com.test.myapp.avro.Email.Builder clearDate() {
date = null;
fieldSetFlags()[1] = false;
return this;
}
/** Gets the value of the 'from' field */
public com.test.myapp.avro.EmailAddress getFrom() {
return from;
}
/** Sets the value of the 'from' field */
public com.test.myapp.avro.Email.Builder setFrom(com.test.myapp.avro.EmailAddress value) {
validate(fields()[2], value);
this.from = value;
fieldSetFlags()[2] = true;
return this;
}
/** Checks whether the 'from' field has been set */
public boolean hasFrom() {
return fieldSetFlags()[2];
}
/** Clears the value of the 'from' field */
public com.test.myapp.avro.Email.Builder clearFrom() {
from = null;
fieldSetFlags()[2] = false;
return this;
}
/** Gets the value of the 'subject' field */
public java.lang.CharSequence getSubject() {
return subject;
}
/** Sets the value of the 'subject' field */
public com.test.myapp.avro.Email.Builder setSubject(java.lang.CharSequence value) {
validate(fields()[3], value);
this.subject = value;
fieldSetFlags()[3] = true;
return this;
}
/** Checks whether the 'subject' field has been set */
public boolean hasSubject() {
return fieldSetFlags()[3];
}
/** Clears the value of the 'subject' field */
public com.test.myapp.avro.Email.Builder clearSubject() {
subject = null;
fieldSetFlags()[3] = false;
return this;
}
/** Gets the value of the 'body' field */
public java.lang.CharSequence getBody() {
return body;
}
/** Sets the value of the 'body' field */
public com.test.myapp.avro.Email.Builder setBody(java.lang.CharSequence value) {
validate(fields()[4], value);
this.body = value;
fieldSetFlags()[4] = true;
return this;
}
/** Checks whether the 'body' field has been set */
public boolean hasBody() {
return fieldSetFlags()[4];
}
/** Clears the value of the 'body' field */
public com.test.myapp.avro.Email.Builder clearBody() {
body = null;
fieldSetFlags()[4] = false;
return this;
}
/** Gets the value of the 'tos' field */
public java.util.List<com.test.myapp.avro.EmailAddress> getTos() {
return tos;
}
/** Sets the value of the 'tos' field */
public com.test.myapp.avro.Email.Builder setTos(java.util.List<com.test.myapp.avro.EmailAddress> value) {
validate(fields()[5], value);
this.tos = value;
fieldSetFlags()[5] = true;
return this;
}
/** Checks whether the 'tos' field has been set */
public boolean hasTos() {
return fieldSetFlags()[5];
}
/** Clears the value of the 'tos' field */
public com.test.myapp.avro.Email.Builder clearTos() {
tos = null;
fieldSetFlags()[5] = false;
return this;
}
/** Gets the value of the 'ccs' field */
public java.util.List<com.test.myapp.avro.EmailAddress> getCcs() {
return ccs;
}
/** Sets the value of the 'ccs' field */
public com.test.myapp.avro.Email.Builder setCcs(java.util.List<com.test.myapp.avro.EmailAddress> value) {
validate(fields()[6], value);
this.ccs = value;
fieldSetFlags()[6] = true;
return this;
}
/** Checks whether the 'ccs' field has been set */
public boolean hasCcs() {
return fieldSetFlags()[6];
}
/** Clears the value of the 'ccs' field */
public com.test.myapp.avro.Email.Builder clearCcs() {
ccs = null;
fieldSetFlags()[6] = false;
return this;
}
/** Gets the value of the 'bccs' field */
public java.util.List<com.test.myapp.avro.EmailAddress> getBccs() {
return bccs;
}
/** Sets the value of the 'bccs' field */
public com.test.myapp.avro.Email.Builder setBccs(java.util.List<com.test.myapp.avro.EmailAddress> value) {
validate(fields()[7], value);
this.bccs = value;
fieldSetFlags()[7] = true;
return this;
}
/** Checks whether the 'bccs' field has been set */
public boolean hasBccs() {
return fieldSetFlags()[7];
}
/** Clears the value of the 'bccs' field */
public com.test.myapp.avro.Email.Builder clearBccs() {
bccs = null;
fieldSetFlags()[7] = false;
return this;
}
@Override
public Email build() {
try {
Email record = new Email();
record.message_id = fieldSetFlags()[0] ? this.message_id : (java.lang.CharSequence) defaultValue(fields()[0]);
record.date = fieldSetFlags()[1] ? this.date : (java.lang.Long) defaultValue(fields()[1]);
record.from = fieldSetFlags()[2] ? this.from : (com.test.myapp.avro.EmailAddress) defaultValue(fields()[2]);
record.subject = fieldSetFlags()[3] ? this.subject : (java.lang.CharSequence) defaultValue(fields()[3]);
record.body = fieldSetFlags()[4] ? this.body : (java.lang.CharSequence) defaultValue(fields()[4]);
record.tos = fieldSetFlags()[5] ? this.tos : (java.util.List<com.test.myapp.avro.EmailAddress>) defaultValue(fields()[5]);
record.ccs = fieldSetFlags()[6] ? this.ccs : (java.util.List<com.test.myapp.avro.EmailAddress>) defaultValue(fields()[6]);
record.bccs = fieldSetFlags()[7] ? this.bccs : (java.util.List<com.test.myapp.avro.EmailAddress>) defaultValue(fields()[7]);
return record;
} catch (Exception e) {
throw new org.apache.avro.AvroRuntimeException(e);
}
}
}
}
答案 0 :(得分：1)
我认为映射器中存在问题。当你声明：
private static class MyAvroMapper extends Mapper<Text, Email, Email, Text> {
你告诉hadoop，你希望这对夫妇（文本，电子邮件）作为密钥的类型以及输入的值和夫妻（电子邮件，文本）作为类型映射器将发出的键和值（请注意，这是为类声明为泛型的四种类型。
但是当你写下这样的签名时：
protected void map(Email email, NullWritable value, Context context) throws IOException, InterruptedException {
你告诉hadoop输入的密钥和值类型是Email和NullWritable，因此是例外。