List list=new ArrayList();
list.add(1);
list.add(2);
list.add(3);

String teststringlist=objectMapper.writeValueAsString(list);
System.out.println(teststringlist);

[1,2,3]

public class student {
private int age=10;
private String name="hhh"; 
  public String[] list={"hao","haouhao","keyi"};
  public Date time=new Date();
     public int getAge() {
          return age;
     }
     public void setAge(int age) {
          this.age = age;
     }
     public String getName() {
          return name;
     }
     public void setName(String name) {
          this.name = name;
     }
}

student st=new student();
String teststringstu=objectMapper.writeValueAsString(st);
System.out.println(teststringstu);

{"list":["hao","haouhao","keyi"],"time":1375429228382,"name":"hhh","age":10}

objectMapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false)

student st=new student();
java.text.DateFormat myFormat = new java.text.SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
objectMapper.getSerializationConfig().setDateFormat(myFormat);
String teststringstu=objectMapper.writeValueAsString(st);
System.out.println(teststringstu);

{"list":["hao","haouhao","keyi"],"time":"2013-08-02 03:48:20","name":"hhh","age":10}

student st=new student();
JsonGenerator jsonGenerator = objectMapper.getJsonFactory().createJsonGenerator(System.out, JsonEncoding.UTF8);
jsonGenerator.writeObject(st); 
System.out.println();

{"list":["hao","haouhao","keyi"],"time":1375429228382,"name":"hhh","age":10}

String test1="{"objectID":357,"geoPoints":[{"x":504604.59802246094,"y":305569.9150390625}]}"

public class testJsonClass
 {
    public int objectID;
    public List geoPoints=new ArrayList();
}

testJsonClass testClass= objectMapper.readValue(test1, testJsonClass.class);

System.out.println(testClass.objectID);
System.out.println(testClass.geoPoints)

357
[{x=504604.59802246094, y=305569.9150390625}]

String json = "{"error":0,"data":{"name":"ABC","age":20,"phone":{"home":"abc","mobile":"def"},"friends":[{"name":"DEF","phone":{"home":"hij","mobile":"klm"}},{"name":"GHI","phone":{"home":"nop","mobile":"qrs"}}]},"other":{"nickname":[]}}"。

System.out.println(maps.get("error"));
System.out.println((Object)(maps.get("data").get("phone")))

0
{home=abc, mobile=def}

String test="{"results":[{"objectID":357,"geoPoints":[{"x":504604.59802246094,"y":305569.9150390625}]},{"objectID":358,"geoPoints":[{"x":504602.2680053711,"y":305554.43603515625}]}]}";

JsonNode node= objectMapper.readTree(test);   //将Json串以树状结构读入内存
JsonNode contents=node.get("results");//得到results这个节点下的信息
for(int i=0;i<contents.size();i++) //遍历results下的信息，size()函数可以得节点所包含的的信息的个数，类似于数组的长度
{
System.out.println(contents.get(i).get("objectID").getIntValue()); //读取节点下的某个子节点的值
JsonNode geoNumber=contents.get(i).get("geoPoints");
for(int j=0;j<geoNumber.size();j++)   //循环遍历子节点下的信息
{
System.out.println(geoNumber.get(j).get("x").getDoubleValue()+" "+geoNumber.get(j).get("y").getDoubleValue());
}
}

357
504604.59802246094 305569.9150390625
358
504602.2680053711 305554.43603515625