Jsonlib实现Json字符串和Java对象的互相转换

版本：json-lib-2.2.3.jar

package com.zzj.jsonlib;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import net.sf.json.JSONObject;

import com.zzj.jsonlib.user.Address;
import com.zzj.jsonlib.user.Order;

public class JsonTest {

public static void main(String[] args) {
User user = new User();
user.setUsername("zhangsan");
user.setPassword("123");
Address address = new Address();
address.setState("Guangdong");
address.setCity("Shenzhen");
user.setAddress(address);

List<Order> orders = new ArrayList<Order>();
for (int i = 0; i < 2; i++) {
Order order = new Order();
order.setOrderId("orderId_" + i);
order.setStatus("status_" + i);
orders.add(order);
}
user.setOrders(orders);

// 对象转Json字符串
System.out.println("-----序列化-----");
String jsonStr = bean2JsonStr(user);
System.out.println(jsonStr);
// Json字符串转对象
System.out.println("-----反序列化-----");
String jsonStr2 = "{\"Id\":\"123\",\"address\":{\"city\":\"Shenzhen\",\"state\":\"Guangdong\"}," +
"\"orders\":[{\"orderId\":\"orderId_0\",\"status\":\"status_0\"}," +
"{\"orderId\":\"orderId_1\",\"status\":\"status_1\"}]," +
"\"password\":\"123\",\"username\":\"zhangsan\"}";
Map<String, Class<?>> classes = new HashMap<String, Class<?>>();
classes.put("orders", Order.class);
User user2 = (User) jsonStr2Bean(jsonStr2, User.class, classes);
System.out.println(user2);
}

static Object jsonStr2Bean(String jsonStr, Class<?> clazz) {
return jsonStr2Bean(jsonStr, clazz, null);
}

/**
*
* @param jsonStr
* @param clazz
* @param classes 集合字段类型
* @return
*/
static Object jsonStr2Bean(String jsonStr, Class<?> clazz, Map<String, Class<?>> classes){
JSONObject jsonObject = JSONObject.fromObject(jsonStr);
return JSONObject.toBean(jsonObject, clazz, classes);
}

static String bean2JsonStr(Object object){
JSONObject jsonObject = JSONObject.fromObject(object);
return jsonObject.toString();
}
}

User：

package com.zzj.jsonlib;

import java.util.List;

import com.zzj.jsonlib.user.Address;
import com.zzj.jsonlib.user.Order;

public class User {
private String username;
private String password;
private Address address;
private List<Order> orders;

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

public Address getAddress() {
return address;
}

public void setAddress(Address address) {
this.address = address;
}

public List<Order> getOrders() {
return orders;
}

public void setOrders(List<Order> orders) {
this.orders = orders;
}

@Override
public String toString() {
return "User [address=" + address + ", orders=" + orders
+ ", password=" + password + ", username=" + username + "]";
}

}

Order：

package com.zzj.jsonlib.user;

public class Order {
private String orderId;
private String status;

public String getOrderId() {
return orderId;
}

public void setOrderId(String orderId) {
this.orderId = orderId;
}

public String getStatus() {
return status;
}

public void setStatus(String status) {
this.status = status;
}

@Override
public String toString() {
return "Order [orderId=" + orderId + ", status=" + status + "]";
}

}

Address：

package com.zzj.jsonlib.user;

public class Address {
private String state;
private String city;

public String getState() {
return state;
}

public void setState(String state) {
this.state = state;
}

public String getCity() {
return city;
}

public void setCity(String city) {
this.city = city;
}

@Override
public String toString() {
return "Address [city=" + city + ", state=" + state + "]";
}

}

输出结果：

-----序列化-----
{"address":{"city":"Shenzhen","state":"Guangdong"},"orders":[{"orderId":"orderId_0","status":"status_0"},{"orderId":"orderId_1","status":"status_1"}],"password":"123","username":"zhangsan"}
-----反序列化-----
[framework] 2015-10-29 14:38:02,609 - net.sf.json.JSONObject -0    [main] WARN  net.sf.json.JSONObject  - Tried to assign property Id:java.lang.String to bean of class com.zzj.jsonlib.User
User [address=Address [city=Shenzhen, state=Guangdong], orders=[Order [orderId=orderId_0, status=status_0], Order [orderId=orderId_1, status=status_1]], password=123, username=zhangsan]

在反序列化时，Json字符串有冗余，但是并没有抛出异常，只是输出了警告。这种冗余指的是简单属性冗余，如果有复杂属性冗余（例如User中没有定义Address），则会抛出错误Unknown property 'Address'。