json和bean的转换工具Jackson ObjectMapper类使用解析

/**
*   Jackson ObjectMapper类
*/
//ObjectMapper类是Jackson库的主要类。它提供一些功能将转换成Java对象匹配JSON结构，反之亦然。它使用JsonParser和JsonGenerator的实例实现JSON实际的读/写。
//以下是org.codehaus.jackson.map.ObjectMapper类的声明：

public class ObjectMapper
extends ObjectCodec
implements Versioned
// 演示实例：
import java.io.IOException;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.map.SerializationConfig;

public class JacksonTester {
public static void main(String args[]){
ObjectMapper mapper = new ObjectMapper();
String jsonString = "{\"name\":\"Mahesh\", \"age\":21}";

//map json to student
try {
Student student = mapper.readValue(jsonString, Student.class);
System.out.println(student);
mapper.enable(SerializationConfig.Feature.INDENT_OUTPUT);
//把对象转成json string类型的
jsonString = mapper.writeValueAsString(student);
System.out.println(jsonString);

} catch (JsonParseException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}

class Student {
private String name;
private int age;
public Student(){}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String toString(){
return "Student [ name: "+name+", age: "+ age+ " ]";
}
}

//输出结果
Student [ name: Mahesh, age: 21 ]
{
"name" : "Mahesh",
"age" : 21
}