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Java object, Json, Xml conversion tool Jackson is used

黄舟

Feb 22, 2017 pm 03:02 PM

It is very common to convert an object into a string in Json format in a Java project. There are many toolkits that can achieve this requirement, such as Gson, JSON-lib , Jackson and so on. This article mainly introduces the use of Jackson. In addition to converting Java objects and Json strings, Jackson can also convert Java objects into Xml format. It is relatively simple to use and is said to be relatively efficient.
For Jackson's jar package, we can download it from the maven resource library: http://www.php.cn/

The required jar package is as follows, just search and download it by name.

Java object, Json, Xml conversion tool Jackson is used

Next to write the test case, we need a java class:

package com.csii.jackson.object;
public class Book{    
private String name;    
private int price;    
public String getName() {        
return name;
    }    public void setName(String name) {        
    this.name = name;
    }    public int getPrice() {        
    return price;
    }    public void setPrice(int price) {        
    this.price = price;
    }    public Book() {
 
    }    public Book(String name,int price) {        
    this.name = name;        
    this.price = price;
    } 
    @Override    
    public String toString() { 
        return "name:" + name +"; price:" + price;
    }
 
}

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1. Convert the Java object to a Json string:

@Test    public void testGenJson()
{
    ObjectMapper objMapper = new ObjectMapper();
    Book book = new Book("Think in Java",100);        try {
        jsonGen = objMapper.getJsonFactory().createJsonGenerator(System.out,JsonEncoding.UTF8);
        jsonGen.writeObject(book);
    } catch (IOException e) { 
        e.printStackTrace();
    } 
}

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Run the test method, console output:

1	`{"name":"Think in Java","price":100}`

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2. Convert the Json string to a Java object:

/*
 * Json转Java对象
 */
@Test    public void testGenObjByJson()
{
    ObjectMapper objMapper = new ObjectMapper();
    String json = "{\"name\":\"Think in Java\",\"price\":100}"; 
    try {
        Book book = objMapper.readValue(json, Book.class);
        System.out.println(book);
    } catch (IOException e) { 
        e.printStackTrace();
    }  
}

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Since we have rewritten the toString method of the Book class, run the test method, Console output:

1	`name:Think in Java; price:100`

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3. Convert Java object to Xml format:

/*
 * Java对象转xml
 */
@Test    public void testGenXml()
{
    XmlMapper xmlMapper = new XmlMapper();
 
    Book book = new Book("Think in Java",100);        try {
        String xmlStr =  xmlMapper.writeValueAsString(book);
        System.out.println(xmlStr);
    } catch (JsonProcessingException e) { 
        e.printStackTrace();
    }
}

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Run the test method, console output:

1	`<Book xmlns=""><name>Think in Java</name><price>100</price></Book>`

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4. Convert xml format string Convert to Java object:

/*
 * xml转Java对象
 */
@Test    public void testGenObjByXml()
{
    XmlMapper xmlMapper = new XmlMapper();
    String xmlStr = "<Book><name>Think in Java</name><price>100</price></Book>"; 
    try {
        Book book = xmlMapper.readValue(xmlStr, Book.class);
        System.out.println(book);
    } catch (IOException e) {            // TODO Auto-generated catch block
        e.printStackTrace();
    }
 
}

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Output content:

1	`name:Think in Java; price:100`

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Complete test case code:

package com.csii.jackson.test;
import java.io.IOException;
import org.junit.Test;
import com.csii.jackson.object.Book;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
@SuppressWarnings("deprecation")
public class JsonTest { 
    private JsonGenerator jsonGen = null;
    /*
     * Java对象转 Json
     */
    @Test
    public void testGenJson()
    {
        ObjectMapper objMapper = new ObjectMapper();
        Book book = new Book("Think in Java",100);
        try {
            jsonGen = objMapper.getJsonFactory().createJsonGenerator(System.out,JsonEncoding.UTF8);
            jsonGen.writeObject(book);
        } catch (IOException e) { 
            e.printStackTrace();
        } 
    }    /*
     * Json转Java对象
     */
    @Test
    public void testGenObjByJson()
    {
        ObjectMapper objMapper = new ObjectMapper();
        String json = "{\"name\":\"Think in Java\",\"price\":100}"; 
        try {
            Book book = objMapper.readValue(json, Book.class);
            System.out.println(book);
        } catch (IOException e) { 
            e.printStackTrace();
        }  
    }    /*
     * Java对象转xml
     */
    @Test
    public void testGenXml()
    {
        XmlMapper xmlMapper = new XmlMapper();
 
        Book book = new Book("Think in Java",100);
        try {
            String xmlStr =  xmlMapper.writeValueAsString(book);
            System.out.println(xmlStr);
        } catch (JsonProcessingException e) { 
            e.printStackTrace();
        }
    }    /*
     * xml转Java对象
     */
    @Test
    public void testGenObjByXml()
    {
        XmlMapper xmlMapper = new XmlMapper();
        String xmlStr = "<Book><name>Think in Java</name><price>100</price></Book>"; 
        try {
            Book book = xmlMapper.readValue(xmlStr, Book.class);
            System.out.println(book);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
 
    }
}

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Convert an object into a Json format string in a Java project It is very common, and there are many toolkits that can meet this requirement, such as Gson, JSON-lib, Jackson, etc. This article mainly introduces the use of Jackson. In addition to converting Java objects and Json strings, Jackson can also convert Java objects into Xml format. It is relatively simple to use and is said to be relatively efficient.
For Jackson's jar package, we can download it from the maven resource library: http://www.php.cn/

The required jar package is as follows, just search and download it by name.

Java object, Json, Xml conversion tool Jackson is used

Next to write the test case, we need a java class:

package com.csii.jackson.object;
public class Book{    
private String name;    
private int price;    
public String getName() {        
return name;
    }    public void setName(String name) {        
    this.name = name;
    }    public int getPrice() {        
    return price;
    }    public void setPrice(int price) {        
    this.price = price;
    }    public Book() {
 
    }    public Book(String name,int price) {        
    this.name = name;        
    this.price = price;
    } 
    @Override    
    public String toString() { 
        return "name:" + name +"; price:" + price;
    }
 
}

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1. Convert the Java object to a Json string:

@Test    public void testGenJson()
{
    ObjectMapper objMapper = new ObjectMapper();
    Book book = new Book("Think in Java",100);        try {
        jsonGen = objMapper.getJsonFactory().createJsonGenerator(System.out,JsonEncoding.UTF8);
        jsonGen.writeObject(book);
    } catch (IOException e) { 
        e.printStackTrace();
    } 
}

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Run the test method, console output:

1	`{"name":"Think in Java","price":100}`

Copy after login

2. Convert the Json string to a Java object:

/*
 * Json转Java对象
 */
@Test    public void testGenObjByJson()
{
    ObjectMapper objMapper = new ObjectMapper();
    String json = "{\"name\":\"Think in Java\",\"price\":100}"; 
    try {
        Book book = objMapper.readValue(json, Book.class);
        System.out.println(book);
    } catch (IOException e) { 
        e.printStackTrace();
    }  
}

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Since we have rewritten the toString method of the Book class, run the test method, Console output:

1	`name:Think in Java; price:100`

Copy after login

3. Convert Java object to Xml format:

/*
 * Java对象转xml
 */
@Test    public void testGenXml()
{
    XmlMapper xmlMapper = new XmlMapper();
 
    Book book = new Book("Think in Java",100);        try {
        String xmlStr =  xmlMapper.writeValueAsString(book);
        System.out.println(xmlStr);
    } catch (JsonProcessingException e) { 
        e.printStackTrace();
    }
}

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Run the test method, console output:

1	`<Book xmlns=""><name>Think in Java</name><price>100</price></Book>`

Copy after login

4. Convert xml format string Convert to Java object:

/*
 * xml转Java对象
 */
@Test    public void testGenObjByXml()
{
    XmlMapper xmlMapper = new XmlMapper();
    String xmlStr = "<Book><name>Think in Java</name><price>100</price></Book>"; 
    try {
        Book book = xmlMapper.readValue(xmlStr, Book.class);
        System.out.println(book);
    } catch (IOException e) {            // TODO Auto-generated catch block
        e.printStackTrace();
    }
 
}

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Output content:

1	`name:Think in Java; price:100`

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Complete test case code:

package com.csii.jackson.test;
import java.io.IOException;
import org.junit.Test;
import com.csii.jackson.object.Book;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.xml.XmlMapper;
@SuppressWarnings("deprecation")
public class JsonTest { 
    private JsonGenerator jsonGen = null;
    /*
     * Java对象转 Json
     */
    @Test
    public void testGenJson()
    {
        ObjectMapper objMapper = new ObjectMapper();
        Book book = new Book("Think in Java",100);
        try {
            jsonGen = objMapper.getJsonFactory().createJsonGenerator(System.out,JsonEncoding.UTF8);
            jsonGen.writeObject(book);
        } catch (IOException e) { 
            e.printStackTrace();
        } 
    }    /*
     * Json转Java对象
     */
    @Test
    public void testGenObjByJson()
    {
        ObjectMapper objMapper = new ObjectMapper();
        String json = "{\"name\":\"Think in Java\",\"price\":100}"; 
        try {
            Book book = objMapper.readValue(json, Book.class);
            System.out.println(book);
        } catch (IOException e) { 
            e.printStackTrace();
        }  
    }    /*
     * Java对象转xml
     */
    @Test
    public void testGenXml()
    {
        XmlMapper xmlMapper = new XmlMapper();
 
        Book book = new Book("Think in Java",100);
        try {
            String xmlStr =  xmlMapper.writeValueAsString(book);
            System.out.println(xmlStr);
        } catch (JsonProcessingException e) { 
            e.printStackTrace();
        }
    }    /*
     * xml转Java对象
     */
    @Test
    public void testGenObjByXml()
    {
        XmlMapper xmlMapper = new XmlMapper();
        String xmlStr = "<Book><name>Think in Java</name><price>100</price></Book>"; 
        try {
            Book book = xmlMapper.readValue(xmlStr, Book.class);
            System.out.println(book);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
 
    }
}

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