jackson框架解析json

Jackson解析的速度算是同类框架中最快的，同时也是Spring MVC中内置使用的解析方式。

准备工作：

下载jar包：http://jackson.codehaus.org/1.7.6/jackson-all-1.7.6.jar

这个jar包在我的Demo中已经包含了，可以直接下载Demo：http://download.csdn.net/detail/u012251822/6877943

并将jar包添加到libs中

package com.example.jacksontest;

import org.codehaus.jackson.map.ObjectMapper;

public class JsonUtils {
static ObjectMapper objectMapper;

public static <T> T readValue(String content, Class<T> valueType) {
if (objectMapper == null) {
objectMapper = new ObjectMapper();
}
try {
return objectMapper.readValue(content, valueType);
} catch (Exception e) {
e.printStackTrace();
}

return null;
}

public static String toJSon(Object object) {
if (objectMapper == null) {
objectMapper = new ObjectMapper();
}
try {
return objectMapper.writeValueAsString(object);
} catch (Exception e) {
e.printStackTrace();
}

return null;
}

}

package com.example.jacksontest;

import java.io.IOException;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.type.TypeFactory;
import org.codehaus.jackson.type.TypeReference;
import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import com.example.jacksongtest.R;

public class MainActivity extends Activity {

public static ObjectMapper objectMapper = new ObjectMapper();

private TextView mBeanTextView;
private TextView mBeanListTextView;
private TextView mBeanMapTextView;
private TextView mBeanMapListTextView;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mBeanTextView = (TextView) findViewById(R.id.showBean);
mBeanListTextView = (TextView) findViewById(R.id.showList);
mBeanMapTextView = (TextView) findViewById(R.id.showMap);
mBeanMapListTextView = (TextView) findViewById(R.id.showMapList);

// 1.读取Bean类型json
String resultStr = new String();
String json = "{\"userName\": \"a\",\"password\":\"c\"}";
resultStr = JsonUtils.readValue(json, User.class).toString();
mBeanTextView.setText(resultStr);

// 2.读取List<Bean>类型json
json = "[{\"userName\": \"a\",\"password\":\"c\"},{\"userName\": \"b\",\"password\":\"d\"}]";
User[] users = JsonUtils.readValue(json, User[].class);
List<User> userList = Arrays.asList(users);
StringBuffer result = new StringBuffer();
for (int i = 0; i < userList.size(); i++) {
result.append(userList.get(i).toString() + "\t");
}
mBeanListTextView.setText(result);

// 3.1.读取Map<T,E>类型json：第一种方法TypeFactory
json = "{\"A\":{\"userName\": \"a\",\"password\":\"c\"},"
+ "\"B\":{\"userName\":\"b\",\"password\":\"d\"}}";
Map<String, User> usersMap = (Map<String, User>) readJsonBeanInMap(
json, String.class, User.class);
Set<String> keys = usersMap.keySet();
result = new StringBuffer();
for (Iterator<String> it = keys.iterator(); it.hasNext();) {
result.append(usersMap.get(it.next()).toString() + "\t");
}
mBeanMapTextView.setText(result);

// 3.2.读取Map<T,E>类型json：第二种方法TypeReference
readJsonBeanInMap(json);

// 4.读取List<Map<T,E>>类型json：TypeReference
json = "[{\"A\":{\"userName\": \"a\",\"password\":\"a\"},\"C\":{\"userName\": \"c\",\"password\":\"c\"}},"
+ "{\"B\":{\"userName\":\"b\",\"password\":\"b\"}}]";
readJsonBeanInMapInList(json);

}

/**
* 读取Map<-Bean>类型json
*/
public void readJsonBeanInMap(String json) {
ObjectMapper objectMapper = new ObjectMapper();
try {
Map<String, User> users = objectMapper.readValue(json,
new TypeReference<Map<String, User>>() {
});
Set<String> keys = users.keySet();
StringBuffer result = new StringBuffer();
for (Iterator<String> it = keys.iterator(); it.hasNext();) {
result.append(users.get(it.next()).toString() + "\t");
}
System.out.println(result);
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* 读取Map<-Bean>类型json
*
* @param <T>
* @param <E>
*/
public <T, E> Map<T, E> readJsonBeanInMap(String json, Class<T> keyType,
Class<E> valueType) {
try {
Map<T, E> map = objectMapper.readValue(json,
TypeFactory.mapType(HashMap.class, keyType, valueType));
return map;
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}

/**
* 读取List<-Map<-String,Bean>>类型json
*/
public void readJsonBeanInMapInList(String json) {
try {
List<Map<String, User>> users = objectMapper.readValue(json,
new TypeReference<List<Map<String, User>>>() {
});
StringBuffer result = new StringBuffer();
for (int i = 0; i < users.size(); i++) {
Map<String, User> tempMap = users.get(i);
Set<String> keys = tempMap.keySet();
for (Iterator<String> it = keys.iterator(); it.hasNext();) {
result.append(tempMap.get(it.next()).toString() + "\t");
}
}
mBeanMapListTextView.setText(result);
} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
>

<TextView
android:id="@+id/showBeanTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/bean" />

<TextView
android:id="@+id/showBean"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />

<TextView
android:id="@+id/showListTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="@string/bean_list" />

<TextView
android:id="@+id/showList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />

<TextView
android:id="@+id/showMapTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="@string/bean_map" />

<TextView
android:id="@+id/showMap"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />

<TextView
android:id="@+id/showMapListTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="10dp"
android:text="@string/bean_map_list" />

<TextView
android:id="@+id/showMapList"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />

</LinearLayout>

Demo下载：http://download.csdn.net/detail/u012251822/6877943