如何在java中使用jackson将输入字符串转换为json字符串或json对象
如何在java中使用jackson将输入字符串转换为json字符串或json对象 提前感谢此处记录并引用了以下内容: Jackson是一个高性能JSON处理器Java库。在本教程中,我们将向您展示如何使用Jackson的数据绑定将Java对象转换为JSON或从JSON转换为Java对象如何在java中使用jackson将输入字符串转换为json字符串或json对象,java,jackson,Java,Jackson,如何在java中使用jackson将输入字符串转换为json字符串或json对象 提前感谢此处记录并引用了以下内容: Jackson是一个高性能JSON处理器Java库。在本教程中,我们将向您展示如何使用Jackson的数据绑定将Java对象转换为JSON或从JSON转换为Java对象 package com.mkyong.core; import java.util.ArrayList; import java.util.List; public class User { pri
package com.mkyong.core;
import java.util.ArrayList;
import java.util.List;
public class User {
private int age = 29;
private String name = "mkyong";
private List<String> messages = new ArrayList<String>() {
{
add("msg 1");
add("msg 2");
add("msg 3");
}
};
//getter and setter methods
@Override
public String toString() {
return "User [age=" + age + ", name=" + name + ", " +
"messages=" + messages + "]";
}
}
对于对象/json转换,您需要了解以下两种方法:
//1. Convert Java object to JSON format
ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(new File("c:\\user.json"), user);
//2. Convert JSON to Java object
ObjectMapper mapper = new ObjectMapper();
User user = mapper.readValue(new File("c:\\user.json"), User.class);
注意:writeValue()和readValue()都有许多重载方法来支持不同类型的输入和输出。一定要检查一下
<repositories>
<repository>
<id>codehaus</id>
<url>http://repository.codehaus.org/org/codehaus</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.8.5</version>
</dependency>
</dependencies>
输出
{"age":29,"messages":["msg 1","msg 2","msg 3"],"name":"mkyong"}
User [age=29, name=mkyong, messages=[msg 1, msg 2, msg 3]]
注
上面的JSON输出很难读取。您可以通过启用“漂亮打印”功能来增强它package com.mkyong.core;
import java.io.File;
import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class JacksonExample {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
try {
// read from file, convert it to user class
User user = mapper.readValue(new File("c:\\user.json"), User.class);
// display to console
System.out.println(user);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
{"age":29,"messages":["msg 1","msg 2","msg 3"],"name":"mkyong"}
User [age=29, name=mkyong, messages=[msg 1, msg 2, msg 3]]
这在以下文件中记录并引用:
Jackson是一个高性能JSON处理器Java库。在本教程中,我们将向您展示如何使用Jackson的数据绑定将Java对象转换为JSON
package com.mkyong.core;
import java.util.ArrayList;
import java.util.List;
public class User {
private int age = 29;
private String name = "mkyong";
private List<String> messages = new ArrayList<String>() {
{
add("msg 1");
add("msg 2");
add("msg 3");
}
};
//getter and setter methods
@Override
public String toString() {
return "User [age=" + age + ", name=" + name + ", " +
"messages=" + messages + "]";
}
}
对于对象/json转换,您需要了解以下两种方法:
//1. Convert Java object to JSON format
ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(new File("c:\\user.json"), user);
//2. Convert JSON to Java object
ObjectMapper mapper = new ObjectMapper();
User user = mapper.readValue(new File("c:\\user.json"), User.class);
注意:writeValue()和readValue()都有许多重载方法来支持不同类型的输入和输出。请确保将其签出
<repositories>
<repository>
<id>codehaus</id>
<url>http://repository.codehaus.org/org/codehaus</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.codehaus.jackson</groupId>
<artifactId>jackson-mapper-asl</artifactId>
<version>1.8.5</version>
</dependency>
</dependencies>
输出
{"age":29,"messages":["msg 1","msg 2","msg 3"],"name":"mkyong"}
User [age=29, name=mkyong, messages=[msg 1, msg 2, msg 3]]
注
上面的JSON输出很难阅读。您可以通过启用漂亮的打印功能来增强它package com.mkyong.core;
import java.io.File;
import java.io.IOException;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class JacksonExample {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper();
try {
// read from file, convert it to user class
User user = mapper.readValue(new File("c:\\user.json"), User.class);
// display to console
System.out.println(user);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
{"age":29,"messages":["msg 1","msg 2","msg 3"],"name":"mkyong"}
User [age=29, name=mkyong, messages=[msg 1, msg 2, msg 3]]
在java中,我们可以通过很多方法将字符串转换为json。为此,您可以使用collection HashMap,它在{key:value}对中为您提供值,这可能对您很有用,如果您使用Spring,这可能对您很有帮助
//****************** update The user Info**********************//
@RequestMapping(value = "/update/{id}", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
public @ResponseBody
Status updateMsBuddy(@RequestBody MsBuddyInfo msBuddyInfo){
try{
if(msBuddyService.updateMsBuddy(msBuddyInfo))
return new Status(1, "MsBuddyInfo updated Successfully",+msBuddyInfo.getId());
else
return new Status(1, "unable to updated Profile",+msBuddyInfo.getId());
}
catch(Exception e){
return new Status(0,e.toString());
}
}
在java中,我们可以通过很多方法将字符串转换为json。您可以为此使用collection,HashMap为您提供{key:value}对中的值,这对您可能有用,如果您使用Spring,这对您可能会有所帮助
//****************** update The user Info**********************//
@RequestMapping(value = "/update/{id}", method = RequestMethod.POST, consumes = MediaType.APPLICATION_JSON_VALUE)
public @ResponseBody
Status updateMsBuddy(@RequestBody MsBuddyInfo msBuddyInfo){
try{
if(msBuddyService.updateMsBuddy(msBuddyInfo))
return new Status(1, "MsBuddyInfo updated Successfully",+msBuddyInfo.getId());
else
return new Status(1, "unable to updated Profile",+msBuddyInfo.getId());
}
catch(Exception e){
return new Status(0,e.toString());
}
}
来自journaldev的非常好的教程
您可以使用jackson API的
com.fasterxml.jackson.databind.ObjectMapper
类来读取或创建字符串格式的json对象。journaldev提供的非常好的教程
您可以使用jackson API的
com.fasterxml.jackson.databind.ObjectMapper
类来读取或创建字符串格式的json对象。到目前为止您尝试了什么?(谷歌或stackoverflow上的搜索将是一个简单的选择)您正在谈论的是哪种上下文?您正在处理web服务吗?请提供其他详细信息。公共静态JsonObject jsonStringToJsonObj(字符串jsonString)抛出IOException{ObjectMapper mapper=new ObjectMapper();返回mapper.readValue(jsonString,new TypeReference(){};}到目前为止您尝试了什么?(谷歌或stackoverflow上的搜索将是一个简单的选择)您在哪种上下文中交谈?您正在处理web服务吗?请提供其他详细信息。公共静态JsonObject jsonStringToJsonObj(字符串jsonString)抛出IOException{ObjectMapper mapper=new ObjectMapper();返回mapper.readValue(jsonString,新类型引用(){});}