我正在尝试使用Json Reader来解析.json文件以将记录插入到我的数据库中，但是我在读取文件时遇到了问题。
我故意用try / catch子句打开解析/阅读器的方法，这样我就可以看到错误的来源。
这是json Parser / Reader类：
package cybertech.productions.servicehelpers;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import android.content.Context;
import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonToken;
public class JsonParser {
public void readCardJsonStream1(String cardSet, CarddbAdapter yugiohDB,
Context context) throws IOException {
URL test = new URL(cardSet);
InputStream in = new BufferedInputStream(test.openStream());
JsonReader reader = new JsonReader(new InputStreamReader(in,
"ISO-8859-1"));
String s, s1, s2, levelstr, rankstr, atkstr, defstr, setnumstr, cardpasstr;
int numTotalElements = 0;
int elementsParsed = 0;
reader.beginObject();
s = reader.nextName();
reader.beginObject();
while (reader.hasNext()) {
s = reader.nextName();
if (s.equalsIgnoreCase("p")) { // cards
reader.beginObject();
while (reader.hasNext()) {
s1 = reader.nextName();
if (s1.equalsIgnoreCase("o")) { // card
YugiohCard c;
reader.beginArray();
while (reader.hasNext()) {
reader.beginObject();
c = new YugiohCard();
while (reader.hasNext()) {
s2 = reader.nextName();
if (s2.equalsIgnoreCase("a")) { // name
c.name = reader.nextString();
} else if (s2.equalsIgnoreCase("b")) { // type
c.type = reader.nextString();
} else if (s2.equalsIgnoreCase("c")) { // attribute_type
c.attributeType = reader.nextString();
} else if (s2.equalsIgnoreCase("d")) { // summon_requirements
c.summonRequirements = reader.nextString();
} else if (s2.equalsIgnoreCase("e")) { // description
c.description = reader.nextString();
} else if (s2.equalsIgnoreCase("f")) { // spell
// speed
c.spellSpeed = reader.nextString();
} else if (s2.equalsIgnoreCase("g")) { // level_stars
levelstr = reader.nextString();
c.levelStars = Integer.parseInt(levelstr);
} else if (s2.equalsIgnoreCase("h")) { // rank_stars
rankstr = reader.nextString();
c.rankStars = Integer.parseInt(rankstr);
} else if (s2.equalsIgnoreCase("i")) { // atk_points
atkstr = reader.nextString();
c.atk_stat = Integer.parseInt(atkstr);
} else if (s2.equalsIgnoreCase("j")) { // def_points
defstr = reader.nextString();
c.def_stat = Integer.parseInt(defstr);
} else if (s2.equalsIgnoreCase("n")) { // set
// initials
c.setinit = reader.nextString();
} else if (s2.equalsIgnoreCase("k")) { // set_number
setnumstr = reader.nextString();
c.setNumber = Integer.parseInt(setnumstr);
} else if (s2.equalsIgnoreCase("l")) { // card_number_pass
cardpasstr = reader.nextString();
c.cardnumberPass = Integer
.parseInt(cardpasstr);
}
}
yugiohDB.createDBCard(c);
reader.endObject();
}
reader.endArray();
}
}
reader.endObject();
}
if (s.equalsIgnoreCase("w")) { // num_cards
numTotalElements = reader.nextInt();
}
}
reader.endObject();
reader.close();
}
}
这是我的Json文件：
{
"t": {
"p": {
"o": [
{
"a": "Elemental HERO Absolute Zero",
"b": "Monster/Fusion/Effect",
"c": "WATER",
"d": "1 'HERO' monster + 1 WATER monster",
"e": "Blows up your field, sucks for you",
"f": "NULL",
"g": "8",
"h": "0",
"i": "2500",
"j": "2000",
"n": "YG04",
"k": "001",
"l": "40854197"
},
{
"a": "Elemental HERO Air Neos",
"b": "Monster/Fusion/Effect",
"c": "WIND",
"d": "Hummingbird + Neos",
"e": "Returns to extra at end phase",
"f": "NULL",
"g": "7",
"h": "0",
"i": "2500",
"j": "2000",
"n": "STON",
"k": "034",
"l": "11502550"
},
{
"a": "Cyber Jar",
"b": "Monster/Effect",
"c": "DARK",
"d": "NULL",
"e": "destroys all monsters on the field",
"f": "NULL",
"g": "3",
"h": "0",
"i": "900",
"j": "900",
"n": "MRL",
"k": "077",
"l": "34124316"
},
{
"a": "Wind-Up Carrier Zenmaity",
"b": "MACHINE/Xyz/Effect",
"c": "WATER",
"d": "2 Level 3 monsters",
"e": "Special summon a wind-up from your hand or deck.",
"f": "NULL",
"g": "0",
"h": "3",
"i": "1500",
"j": "1500",
"n": "ORCS",
"k": "044",
"l": "81122844"
},
{
"a": "BRAIN CONTROL",
"b": "Spell",
"c": "Spell",
"d": "NULL",
"e": "Pay 800 Life Points to target 1 face-up monster your opponent controls; take control of that target until the End Phase.",
"f": "Normal",
"g": "0",
"h": "0",
"i": "0",
"j": "0",
"n": "LCYW",
"k": "074",
"l": "87910978"
},
{
"a": "Ring of Destruction",
"b": "Trap",
"c": "Trap",
"d": "NULL",
"e": "Target 1 face-up monster on the field; destroy that target, and if you do, inflict damage to both players equal to that target's ATK.",
"f": "Normal",
"g": "0",
"h": "0",
"i": "0",
"j": "0",
"n": "YG04",
"k": "001",
"l": "40854197"
}
]
},
"v": "2/3/2013"
}
}
这是我创建的方法，用于告诉json文件在我的网站上的位置：
public void CreateYUGIsets() throws MalformedURLException, IOException{
yugiohDB.dropDB();
JsonParser parser = new JsonParser();
String cardSetList = "https://sites.google.com/site/yugiohlibrary/patches/test.json";
parser.readCardJsonStream1(cardSetList, yugiohDB, this);
}
这也是我得到的Logcat错误：
05-15 22:48:49.362: E/AndroidRuntime(476): FATAL EXCEPTION: main
05-15 22:48:49.362: E/AndroidRuntime(476): java.lang.RuntimeException: Unable to start activity ComponentInfo{cybertech.productions.yugiohlibrary/cybertech.productions.yugiohlibrary.LoadingScreen}: java.lang.IllegalStateException: Expected a name but was STRING
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.os.Handler.dispatchMessage(Handler.java:99)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.os.Looper.loop(Looper.java:123)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread.main(ActivityThread.java:3683)
05-15 22:48:49.362: E/AndroidRuntime(476): at java.lang.reflect.Method.invokeNative(Native Method)
05-15 22:48:49.362: E/AndroidRuntime(476): at java.lang.reflect.Method.invoke(Method.java:507)
05-15 22:48:49.362: E/AndroidRuntime(476): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
05-15 22:48:49.362: E/AndroidRuntime(476): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
05-15 22:48:49.362: E/AndroidRuntime(476): at dalvik.system.NativeStart.main(Native Method)
05-15 22:48:49.362: E/AndroidRuntime(476): Caused by: java.lang.IllegalStateException: Expected a name but was STRING
05-15 22:48:49.362: E/AndroidRuntime(476): at com.google.gson.stream.JsonReader.nextName(JsonReader.java:444)
05-15 22:48:49.362: E/AndroidRuntime(476): at cybertech.productions.servicehelpers.JsonParser.readCardJsonStream1(JsonParser.java:36)
05-15 22:48:49.362: E/AndroidRuntime(476): at cybertech.productions.yugiohlibrary.LoadingScreen.CreateYUGIsets(LoadingScreen.java:107)
05-15 22:48:49.362: E/AndroidRuntime(476): at cybertech.productions.yugiohlibrary.LoadingScreen.onCreate(LoadingScreen.java:41)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
05-15 22:48:49.362: E/AndroidRuntime(476): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
05-15 22:48:49.362: E/AndroidRuntime(476): ... 11 more
对于logcat中的这一特定行： cybertech.productions.servicehelpers.JsonParser.readCardJsonStream1（JsonParser.java:36） 05-15 22：48：49.362：E / AndroidRuntime（476）
JsonParser类中的第36行是： s = reader.nextName（）;
当第一个while（）循环开始时，该行就在右边。
任何帮助都将不胜感激。
答案 0 :(得分：4)
您选择了解决JSON文件最繁琐的方法。您正在使用的库（Gson）提供了更简单的方法来处理输入。这是一个仍然进行手动解析的示例：
// Your JSON data here
final String json = "";
// Get the array element corresponding to t->p->o, in the data
final JsonElement rootElem = new JsonParser().parse(json);
final JsonArray jsonArr = rootElem.getAsJsonObject()
.getAsJsonObject("t").getAsJsonObject("p").getAsJsonArray("o");
// Iterate through the JSON array, extracting out card info as we go
final List<Yugioh> cards = new ArrayList<Yugioh>(jsonArr.size());
for (final JsonElement objElem : jsonArr) {
final JsonObject jsonObj = objElem.getAsJsonObject();
final Yugioh card = new Yugioh();
card.setName(jsonObj.get("a").getAsString());
card.setType(jsonObj.get("b").getAsString());
card.setAttributeType(jsonObj.get("c").getAsString());
card.setSummonRequirements(jsonObj.get("d").getAsString());
card.setDescription(jsonObj.get("e").getAsString());
card.setSpellSpeed(jsonObj.get("f").getAsString());
card.setLevelStars(Integer.parseInt(jsonObj.get("g").getAsString()));
card.setRankStars(Integer.parseInt(jsonObj.get("h").getAsString()));
card.setAtkStat(Integer.parseInt(jsonObj.get("i").getAsString()));
card.setDefStat(Integer.parseInt(jsonObj.get("j").getAsString()));
card.setNumber(Integer.parseInt(jsonObj.get("k").getAsString()));
card.setCardNumberPass(Integer.parseInt(jsonObj.get("l")
.getAsString()));
card.setInit(jsonObj.get("n").getAsString());
System.out.println(card);
cards.add(card);
}
请注意代码的可读性。我冒昧地说明了正确使用getter / setter，并修复了一些变量名。通过在mapper类中指示要复制的JSON属性的序列化名称，可以进一步缩短上面的示例。例如，使用此映射器类：
class Yugioh implements Serializable {
private static final long serialVersionUID = -8125568453376399843L;
@SerializedName("a")
private String name;
@SerializedName("b")
private String type;
@SerializedName("c")
private String attributeType;
@SerializedName("d")
private String summonRequirements;
@SerializedName("e")
private String description;
@SerializedName("f")
private String spellSpeed;
@SerializedName("g")
private Integer levelStars;
@SerializedName("h")
private Integer rankStars;
@SerializedName("i")
private Integer atkStat;
@SerializedName("j")
private Integer defStat;
@SerializedName("k")
private Integer number;
@SerializedName("l")
private Integer cardNumberPass;
@SerializedName("n")
private String init;
public Yugioh() {
super();
}
// Getters/Setters here
@Override
public String toString() {
return String.format("Card %s", getName());
}
}
您可以显着缩短反序列化代码：
// Your JSON data here
final String json = "";
// Deserialize JSON into a bunch of objects
final JsonElement rootElem = new JsonParser().parse(json);
final JsonArray jsonArr = rootElem.getAsJsonObject()
.getAsJsonObject("t").getAsJsonObject("p").getAsJsonArray("o");
final List<Yugioh> cards = new Gson().fromJson(jsonArr,
new TypeToken<List<Yugioh>>() {
}.getType());
System.out.println(cards);
死简单。请务必阅读Gson User Guide - 它提供了大量有关利用图书馆的有用信息。