Java与JSON之间的相互转换-4

添加 jar 包支持

jackson-annotations-2.0.5.jarjackson-core-2.0.5.jarjackson-databind-2.0.5.jar

编写工具类

import java.io.IOException;import java.util.List;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.JavaType;import com.fasterxml.jackson.databind.ObjectMapper;public final class JsonUtils {    private static ObjectMapper mapper = new ObjectMapper();    public static String toJson(Object data) throws JsonProcessingException {        return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(data);    }    public static <T> T toObject(String data, Class<T> clazz) throws IOException {        return mapper.readValue(data, clazz);    }    public static <T> List<T> toList(String data, Class<T> clazz) throws IOException {        JavaType beanListType = mapper.getTypeFactory().constructParametricType(List.class, clazz);        return mapper.readValue(data,  beanListType);    }}

测试代码

import java.io.IOException;import java.util.ArrayList;import java.util.List;import model.Person;import org.junit.Test;import com.fasterxml.jackson.core.JsonProcessingException;import util.JsonUtils;public class JsonTest {    /**     * Object ---> JSON     * @throws JsonProcessingException      */    @Test    public void testObjectToJson() throws JsonProcessingException {        Person p = new Person();        p.setName("张三");        p.setAge("18");        p.setAddress("郑州");        String result = JsonUtils.toJson(p);        System.out.println("=== Object ---> JSON ===");        System.out.println(result);    }    /**     * JSON ---> Object     * @throws IOException      */    @Test    public void testJsonToObject() throws IOException {        String data = "{\"address\":\"郑州\",\"age\":\"18\",\"name\":\"张三\"}";        Person p = JsonUtils.toObject(data, Person.class);        System.out.println("=== JSON ---> Object ===");        System.out.println(p);        System.out.println();    }    /**     * List ---> JSON     * @throws JsonProcessingException      */    @Test    public void testListToJson() throws JsonProcessingException {        Person p1 = new Person();        p1.setName("张三");        p1.setAge("18");        p1.setAddress("郑州");        Person p2 = new Person();        p2.setName("李四");        p2.setAge("20");        p2.setAddress("北京");        List<Person> list = new ArrayList<Person>();        list.add(p1);        list.add(p2);        String result = JsonUtils.toJson(list);        System.out.println("=== List ---> JSON ===");        System.out.println(result);        System.out.println();    }    /**     * JSON ---> List     * @throws IOException      */    @Test    public void testJsonToList() throws IOException {        String data = "[{\"address\":\"郑州\",\"age\":\"18\",\"name\":\"张三\"},{\"address\":\"北京\",\"age\":\"20\",\"name\":\"李四\"}]";        List<Person> list = JsonUtils.toList(data, Person.class);        System.out.println("=== JSON ---> List ===");        for (Person person : list) {            System.out.println(person);        }    }}

运行结果

=== JSON ---> Object ===Person [name=张三, age=18, address=郑州]=== List ---> JSON ===[ {  "name" : "张三",  "age" : "18",  "address" : "郑州"}, {  "name" : "李四",  "age" : "20",  "address" : "北京"} ]=== JSON ---> List ===Person [name=张三, age=18, address=郑州]Person [name=李四, age=20, address=北京]=== Object ---> JSON ==={  "name" : "张三",  "age" : "18",  "address" : "郑州"}