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11. Custom Converter
2022-08-10 23:48:00 【If you want to learn, learn Big Wolf】
文章目录
11.1 基本介绍
- SpringBoot 在响应客户端请求时,Encapsulate the submitted data into objects时,使用了内置的转换器
- SpringBoot Custom converters are also supported,This built-in converter is in debug 的时候,可以看到
- 提供了 124 a built-in converter
- 看下源码 GenericConverter-ConvertiblePair
11.2 自定义转换器-应用实例
11.2.1 需求说明：Demonstrate custom converter usage
11.2.2 代码实现
- 修改 save.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Add little monsters</title>
</head>
<body>
<h1>添加妖怪-坐骑[测试封装 POJO]</h1>
<form action="/saveMonster" method="post">
编号： <input name="id" value="100"><br/>
姓名： <input name="name" value="牛魔王"/> <br/>
年龄： <input name="age" value="120"/> <br/>
婚否： <input name="isMarried" value="true"/> <br/>
生日： <input name="birth" value="2000/11/11"/> <br/>
<!--坐骑： <input name="car.name" value="法拉利"/><br/>-->
<!--价格： <input name="car.price" value="99999.9"/>-->
<!--Use custom converter associationsCar, The string as a whole is submitted 使用 ,号 间隔-->
坐骑： <input name="car" value="避水金睛兽,888.8"/><br/>
<input type="submit" value="保存"/>
</form>
</body>
</html>
- 创建自定义转换器 D:\xjs_springboot\springbootweb\src\main\java\com\xjs\springboot\config\WebConfig.java
package com.xjs.springboot.config;
import com.xjs.springboot.bean.Car;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;
import org.springframework.format.FormatterRegistry;
import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
/** * @Author: 谢家升 * @Version: 1.0 */
/** * 解读：@Configuration(proxyBeanMethods = false) * 1. WebConfig 是一个配置类 * 2. proxyBeanMethods = false 表示使用了 lite模式 */
@Configuration(proxyBeanMethods = false)
public class WebConfig {
//注入一个Bean WebMvcConfigurer
@Bean
public WebMvcConfigurer webMvcConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addFormatters(FormatterRegistry registry) {
/** * 解读： * 1. 在 addFormatters 方法中,Add a custom converter * 2. Add custom converters String -> Car * 3. Added custom converters will be registered to converters 容器中 * 4. converters 底层结构是 ConcurrentHashMap 内置有124个转换器[The number of different versions may vary] * 5. 一会儿 Debug */
registry.addConverter(new Converter<String, Car>() {
@Override
public Car convert(String source) {
//source 就是传入的字符串 => 避水金睛兽,888.8
//Add your custom conversion business code here
if (!ObjectUtils.isEmpty(source)) {
Car car = new Car();
String[] split = source.split(",");
car.setName(split[0]);
car.setPrice(Double.parseDouble(split[1]));
return car;
}
return null;
}
});
}
};
}
}
- 完成测试,浏览器 http://localhost:8080/save.html
monster-Monster(id=100, name=牛魔王, age=120, isMarried=true, birth=Sat Nov 11 00:00:00 CST 2000, car=Car(name=避水金睛兽, price=888.8))
- Debug 可以看到我们新增的 Converter
11.2.3 Register the converter in a different way-方便理解
package com.xjs.springboot.config;
import com.xjs.springboot.bean.Car;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;
import org.springframework.format.FormatterRegistry;
import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
/** * @Author: 谢家升 * @Version: 1.0 */
/** * 解读：@Configuration(proxyBeanMethods = false) * 1. WebConfig 是一个配置类 * 2. proxyBeanMethods = false 表示使用了 lite模式 */
@Configuration(proxyBeanMethods = false)
public class WebConfig {
//注入一个Bean WebMvcConfigurer
@Bean
public WebMvcConfigurer webMvcConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addFormatters(FormatterRegistry registry) {
/** * 解读： * 1. 在 addFormatters 方法中,Add a custom converter * 2. Add custom converters String -> Car * 3. Added custom converters will be registered to converters 容器中 * 4. converters 底层结构是 ConcurrentHashMap 内置有124个转换器[The number of different versions may vary] * 5. 一会儿 Debug */
//registry.addConverter(new Converter<String, Car>() {
// @Override
// public Car convert(String source) { //source 就是传入的字符串 => 避水金睛兽,888.8
// //Add your custom conversion business code here
// if (!ObjectUtils.isEmpty(source)) {
//
// Car car = new Car();
// String[] split = source.split(",");
// car.setName(split[0]);
// car.setPrice(Double.parseDouble(split[1]));
// return car;
//
// }
// return null;
// }
//});
//Write another way to register custom converters-方便理解
//1. Create a custom converter first
Converter<String, Car> xjsConverter = new Converter<String, Car>() {
@Override
public Car convert(String source) {
//source 就是传入的字符串 => 避水金睛兽,888.8
//Add your custom conversion business code here
if (!ObjectUtils.isEmpty(source)) {
Car car = new Car();
String[] split = source.split(",");
car.setName(split[0]);
car.setPrice(Double.parseDouble(split[1]));
return car;
}
return null;
}
};
//More converters can also be added
//2. Add converter to converters
registry.addConverter(xjsConverter);
}
};
}
}
----- 细节说明 -----
- Add converter to converters
key=>[源类型->目标类型]- converters 底层是 ConcurrentHashMap
- 其中key是 [源类型->目标类型]
- So when two converters are 源类型 和 目标类型 相同,则会覆盖
- 这里添加的 第3a custom converter 会覆盖 第1a custom converter [都是 String -> Car]
package com.xjs.springboot.config;
import com.xjs.springboot.bean.Car;
import com.xjs.springboot.bean.Monster;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.convert.converter.Converter;
import org.springframework.format.FormatterRegistry;
import org.springframework.util.ObjectUtils;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
/** * @Author: 谢家升 * @Version: 1.0 */
/** * 解读：@Configuration(proxyBeanMethods = false) * 1. WebConfig 是一个配置类 * 2. proxyBeanMethods = false 表示使用了 lite模式 */
@Configuration(proxyBeanMethods = false)
public class WebConfig {
//注入一个Bean WebMvcConfigurer
@Bean
public WebMvcConfigurer webMvcConfigurer() {
return new WebMvcConfigurer() {
@Override
public void addFormatters(FormatterRegistry registry) {
/** * 解读： * 1. 在 addFormatters 方法中,Add a custom converter * 2. Add custom converters String -> Car * 3. Added custom converters will be registered to converters 容器中 * 4. converters 底层结构是 ConcurrentHashMap 内置有124个转换器[The number of different versions may vary] * 5. 一会儿 Debug */
//registry.addConverter(new Converter<String, Car>() {
// @Override
// public Car convert(String source) { //source 就是传入的字符串 => 避水金睛兽,888.8
// //Add your custom conversion business code here
// if (!ObjectUtils.isEmpty(source)) {
//
// Car car = new Car();
// String[] split = source.split(",");
// car.setName(split[0]);
// car.setPrice(Double.parseDouble(split[1]));
// return car;
//
// }
// return null;
// }
//});
//Write another way to register custom converters-方便理解
//1. Create a custom converter first
Converter<String, Car> xjsConverter = new Converter<String, Car>() {
@Override
public Car convert(String source) {
//source 就是传入的字符串 => 避水金睛兽,888.8
//Add your custom conversion business code here
if (!ObjectUtils.isEmpty(source)) {
Car car = new Car();
String[] split = source.split(",");
car.setName(split[0]);
car.setPrice(Double.parseDouble(split[1]));
return car;
}
return null;
}
};
//More converters can also be added
//第2a custom converter
Converter<String, Monster> xjsConverter2 = new Converter<String, Monster>() {
@Override
public Monster convert(String source) {
//source 就是传入的字符串 => 避水金睛兽,888.8
//Add your custom conversion business code here
return null;
}
};
//第3a custom converter
Converter<String, Car> xjsConverter3 = new Converter<String, Car>() {
@Override
public Car convert(String source) {
//source 就是传入的字符串 => 避水金睛兽,888.8
System.out.println("source= " + source);
return null;
}
};
//2. Add converter to converters key-[源类型->目标类型]
// (1) converters 底层是 ConcurrentHashMap
// (2) 其中key是 [源类型->目标类型]
// (3) So when two converters the source type and 目标类型 相同,则会覆盖
// (4) 这里添加的 第3a custom converter 会覆盖 第1a custom converter
registry.addConverter(xjsConverter);
registry.addConverter(xjsConverter2);
registry.addConverter(xjsConverter3);
}
};
}
}
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