这是一个以流方式解析JSON结构的程序。 现在是晚上10点，我的大脑很累，这就是为什么我似乎无法弄清楚为什么我会得到异常： java.io.Exception：Stream关闭。
如果这里的专家可以帮助我摆脱这个例外，我将非常感谢帮助我解决这个问题。
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.util.*;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.*;
import java.util.Properties;
public class JacksonStreaming {
public static void main(String[] args) {
System.out.println("Entered Main");
try {
new JacksonStreaming().getNames();
} catch (Exception e) {
e.printStackTrace();
}
}
ObjectMapper jsonMapper = new ObjectMapper();
JsonFactory jsonFactory = new JsonFactory();
Properties prop = new Properties();
String filePath = "";
final String[] path = new String[] {"myReport", "docReports", "part1/.", "myAnalysis", "matches", "name"};
void getNames() {
System.out.println("Entered getNames");
//final String resourceName = "C:/Users/Ilango/ellyworkspace/JacksonStreamingFindData/src/jsonFormattedModified.json";
JsonNode rootNode;
try {
//InputStream in = getClass().getClassLoader().getResourceAsStream("config.properties");
BufferedReader fileReader = new BufferedReader(new FileReader("C:/Users/Ilango/ellyworkspace/JacksonStreamingFindData/src/jsonFormattedModified.json"));
System.out.println("fileReader is: " + fileReader);
rootNode = jsonMapper.readTree(fileReader);
System.out.println("Return value of jsonMapper.readTree is: " +rootNode);
findByPath(rootNode);
JsonParser jsonParser = jsonFactory.createParser(fileReader);
System.out.println("JsonParser is: " + jsonParser);
int pathIndex = 0;
List<String> names = new ArrayList<String>();
boolean breakOnClose = false;
//try {
//try {
while (jsonParser.nextToken() != null) {
final String fieldName = jsonParser.getCurrentName();
if (fieldName == null) {
continue;
}
if (breakOnClose && fieldName.equals(path[path.length - 2])) {
System.out.println("Stopping search at end of node " + fieldName);
break;
}
if (jsonParser.getCurrentToken() != JsonToken.FIELD_NAME) {
continue;
}
// System.out.println("Field " + fieldName);
if (pathIndex >= path.length - 1) {
if (fieldName.equals(path[path.length - 1])) {
// move from field name to field value.
try {
jsonParser.nextToken();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String name;
//try {
name = jsonParser.getValueAsString();
//} catch (IOException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
//}
if (name == null) {
throw new RuntimeException("No value exists for field " + fieldName);
}
names.add(name);
System.out.println("Found " + fieldName + " value: " + name);
}
} else if (fieldName.equals(path[pathIndex])) {
System.out.println("Found node " + path[pathIndex]);
pathIndex++;
if (pathIndex >= path.length - 1) {
System.out.println("Looking for names ...");
breakOnClose = true;
// prevent breaking on "matches" value json-token.
try {
jsonParser.nextFieldName();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
void findByPath(JsonNode jn) {
System.out.println("Entered findByPath");
JsonNode matchesNamesNode = jn;
for (int i = 0; i < path.length - 1; i++) {
matchesNamesNode = matchesNamesNode.path(path[i]);
}
if (matchesNamesNode.isMissingNode()) {
throw new RuntimeException("No node with names found.");
}
System.out.println("Tree names: " + matchesNamesNode.findValuesAsText("name"));
}
}// end of class JacksonStreaming
def setCount(count: Int) {
this.count = count
}
}
堆栈跟踪：
Entered Main
Entered getNames
fileReader is: java.io.BufferedReader@33e5ccce
Return value of jsonMapper.readTree is: {"type":"ImportantIncidentInfo","incidentTimestamp":"2014-05-15T10:09:27.989-05:00","numOfMatches":4,"myReport":{"docReports":{"part1/.":{"path":["unknown"],"myAnalysis":{"matches":[{"id":{"major":1,"minor":0},"name":"US SSN","position":13,"string":" 636-12-4567 "},{"id":{"major":3,"minor":0},"name":"MasterCard Credit Card Number","position":35,"string":" 5424-1813-6924-3685 "}]},"cleanedUpData":[{"startPosition":0,"endPosition":65,"frameContent":""}],"minedMetadata":{"Content-Encoding":"ISO-8859-1","Content-Type":"text/html; charset=iso-8859-1"},"deducedMetadata":{"Content-Type":"text/html; iso-8859-1"}},"part2/.":{"path":["unknown"],"myAnalysis":{"matches":[{"id":{"major":1,"minor":0},"name":"SSN","position":3,"string":" 636-12-4567\r"},{"id":{"major":3,"minor":0},"name":"MasterCard Credit Card Number","position":18,"string":"\n5424-1813-6924-3685\r"}]},"cleanedUpData":[{"startPosition":0,"endPosition":44,"frameContent":""}],"minedMetadata":{"Content-Encoding":"windows-1252","Content-Type":"text/plain; charset=windows-1252"},"deducedMetadata":{"Content-Type":"text/plain; iso-8859-1"}}}},"whatSetItOffEntry":{"action":"Log","component":{"type":"aComponent","components":[{"type":"PatternComponent","patterns":[1],"not":false}],"not":false},"ticketInfo":{"createIncident":true,"tags":[],"seeRestrictedIds":[{"type":"userGroup","name":"SiteMasters","description":"Group for SiteMasters","masters":["04fb02a2bc0fba"],"members":[],"id":"04fade"}]},"letmeknowInfo":{"createNotification":true,"contactNames":["someguy@gmail.com"]}},"seeRestrictedIds":["04fade66c0"],"status":"New","timeStamps":["2015-05-15T10:09:27.989-05:00"],"count":1}
Entered findByPath
Tree names: [US SSN, MasterCard Credit Card Number]
JsonParser is: com.fasterxml.jackson.core.json.ReaderBasedJsonParser@23223dd8
java.io.IOException: Stream closed
at java.io.BufferedReader.ensureOpen(BufferedReader.java:122)
at java.io.BufferedReader.read(BufferedReader.java:278)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.loadMore(ReaderBasedJsonParser.java:153)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser._skipWSOrEnd(ReaderBasedJsonParser.java:1855)
at com.fasterxml.jackson.core.json.ReaderBasedJsonParser.nextToken(ReaderBasedJsonParser.java:571)
at com.myorg.myapi.JacksonStreaming.getNames(JacksonStreaming.java:55)
at com.myorg.myapi.JacksonStreaming.main(JacksonStreaming.java:19)
答案 0 :(得分：8)
您的代码出现了问题（请参阅注释）：
// you create a BufferedReader (no problems per se)
BufferedReader fileReader = new BufferedReader(new FileReader("C:/Users/Ilango/ellyworkspace/JacksonStreamingFindData/src/jsonFormattedModified.json"));
// this consumes the fileReader stream
rootNode = jsonMapper.readTree(fileReader);
findByPath(rootNode);
// the next line is where the problem is happening
// fileReader has already been consumed, so the call to createParser() must fail
JsonParser jsonParser = jsonFactory.createParser(fileReader); // java.io.IOException: Stream closed
您的问题的解决方案是制作流的副本，或者在已经读取之后不再使用它。