Jackson(ObjectMapper)的简单使用(可转xml)

参考文章：http://www.cnblogs.com/hoojo/archive/2011/04/22/2024628.html (原文章更详细哦,且有介绍xml与java对象的互转)

参考文章作者：hoojo

本例maven配置：

<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.4.1</version>
</dependency>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-jaxrs</artifactId>
<version>1.9.11</version>
</dependency>

测试代码：

import java.io.IOException;

import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.ObjectMapper;

public class TestJackSon {

// 声明两个转换器
private ObjectMapper objectMapper = null; // 一般使用ObjectMapper就已足够
private JsonGenerator jsonGenerator = null; // 需要关闭

/**
* Java对象转换成JSON_1（objectMapper）
*/
public void test1() {
// 实例化转换器
objectMapper = new ObjectMapper();

// 测试
try {
User user = new User("ZhangSan", 25, "abc@163.com");

// 直接输出转化结果到服务台，返回void
System.out.println("直接输出到服务台：");
objectMapper.writeValue(System.out, user); // user可替换为List,Map等等其他类型,都可正常输出

} catch (Exception e) {
e.printStackTrace();
}
}

/**
* Java对象转换成JSON_2（objectMapper）
*/
public void test2() {
// 实例化转换器
objectMapper = new ObjectMapper();

// 测试
try {
User user = new User("ZhangSan", 25, "abc@163.com");
// 返回String
String json = objectMapper.writeValueAsString(user); // user可替换为List,Map等等其他类型,都可正常输出
System.out.println("返回String：");
System.out.println(json);

} catch (Exception e) {
e.printStackTrace();
}
}

/**
* Json转Java对象（objectMapper）
*/
public void test3() {
// 实例化转换器
objectMapper = new ObjectMapper();

// 测试
try {
String json = "{\"name\":\"ZhangSan\",\"age\":25,\"emailAddress\":\"abc@163.com\"}";
User user = objectMapper.readValue(json, User.class);

System.out.println(user.getName() + " | " + user.getAge() + " | " + user.getEmailAddress());
} catch (Exception e) {
e.printStackTrace();
}
}

/**
* jsonGenerator的简单使用
*/
public void test4() {
// 实例化转换器
objectMapper = new ObjectMapper();
try {
jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.out, JsonEncoding.UTF8);
User user = new User("ZhangSan", 25, "abc@163.com");

// 测试
System.out.println("jsonGenerator:");
jsonGenerator.writeObject(user); //直接输出到控制台

// jsonGenerator需要关闭
if (jsonGenerator != null) {
jsonGenerator.flush();
}
if (!jsonGenerator.isClosed()) {
jsonGenerator.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}

/**
* 测试main
*/
public static void main(String[] args) {
TestJackSon test = new TestJackSon();
test.test4();
}

}

class User {

public String name;

public int age;

public String emailAddress;

/**
* 构造函数
*/
public User(String name, int age, String emailAddress) {
super();
this.name = name;
this.age = age;
this.emailAddress = emailAddress;
}

// getters/setters(略)

}

追加记录(2017-02-16)：

可增加如下配置，解决json中属性多于java对象中属性时报错的问题.

objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
XXX xxx = objectMapper.readValue(jsonResult, XXX.class);