Postman使用

简单的Rest控制器

package cc.conyli.controller;


import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("/test")
public class DemoRestController {

    @GetMapping("/hello")
    public String sayHello() {
        return "第一个Spring REST响应";
    }
}

<mvc:annotation-driven>
    <mvc:message-converters register-defaults="true">
        <bean class="org.springframework.http.converter.StringHttpMessageConverter">
            <constructor-arg value="UTF-8" />
        </bean>
    </mvc:message-converters>
</mvc:annotation-driven>

返回JSON字符串

package cc.conyli.controller;

import cc.conyli.entity.Customer;
import cc.conyli.service.CustomerService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/api")
public class CustomerRestController {

    private CustomerService customerService;

    @Autowired
    public CustomerRestController(CustomerService customerService) {
        this.customerService = customerService;
    }

    @GetMapping("/customers")
    public List<Customer> getCustomers() {
        return customerService.getCustomers();
    }
}

@GetMapping("/customers/{customerId}")
public Customer getCustomer(@PathVariable int customerId) {
    List<Customer> customers = customerService.getCustomers();
        return customers.get(customerId - 1);
}

Request processing failed; nested exception is java.lang.IndexOutOfBoundsException: Index: 4, Size: 4

异常处理

1. 编写自定义的错误类和POJO对象
2. 添加@ExceptionHandler来编写一个处理错误的方法
3. 返回POJO对象转换而成的错误信息

package cc.conyli.errorhandler;

public class CustomerErrorResponse {

    private int status;
    private String message;
    private long timeStamp;

    public CustomerErrorResponse(int status, String message, long timeStamp) {
        this.status = status;
        this.message = message;
        this.timeStamp = timeStamp;
    }

    public CustomerErrorResponse() {
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public String getMessage() {
        return message;
    }

    public void setMessage(String message) {
        this.message = message;
    }

    public long getTimeStamp() {
        return timeStamp;
    }

    public void setTimeStamp(long timeStamp) {
        this.timeStamp = timeStamp;
    }

    @Override
    public String toString() {
        return "CustomerErrorResponse{" +
                "status=" + status +
                ", message='" + message + '\'' +
                ", timeStamp=" + timeStamp +
                '}';
    }
}

package cc.conyli.errorhandler;

public class CustomerNotfoundError extends RuntimeException {

    public CustomerNotfoundError(String message) {
        super(message);
    }
}

1. 错误处理方法用@ExceptionHandler注解
2. 错误处理方法要求固定返回ResponseEntity<T>对象，其中的泛型T是我们刚才编写那个转换成JSON的类。ResponseEntity是一个包装了Http响应的类，这个类可以去控制状态码，响应头和体等具体内容，非常方便。
3. 错误处理方法的名称可以是任意名称，但是参数必须是要处理的异常类型，也就是尝试catch的异常类型

@ExceptionHandler
public ResponseEntity<CustomerErrorResponse> handleCustomerNotfoundError(CustomerNotfoundError customerNotfoundError) {
    CustomerErrorResponse customerErrorResponse = new CustomerErrorResponse();

    customerErrorResponse.setStatus(HttpStatus.NOT_FOUND.value());
    customerErrorResponse.setMessage(customerNotfoundError.getMessage());
    customerErrorResponse.setTimeStamp(System.currentTimeMillis());

    return new ResponseEntity<>(customerErrorResponse, HttpStatus.NOT_FOUND);
}

@GetMapping("/customers/{customerId}")
public Customer getCustomer(@PathVariable int customerId) {
    Customer customer = customerService.getCustomer(customerId);
    if (customer == null) {
        throw new CustomerNotfoundError("Customer with id " + customerId + " NOT FOUND!");
    }
    return customer;
}

{
    "status": 404,
    "message": "Customer with id 14 NOT FOUND!",
    "timeStamp": 1553500503641
}

@ExceptionHandler
public ResponseEntity<CustomerErrorResponse> handleNormalException(Exception ex) {
    CustomerErrorResponse customerErrorResponse = new CustomerErrorResponse();

    customerErrorResponse.setStatus(HttpStatus.BAD_REQUEST.value());
    customerErrorResponse.setMessage(ex.getMessage());
    customerErrorResponse.setTimeStamp(System.currentTimeMillis());

    return new ResponseEntity<>(customerErrorResponse, HttpStatus.BAD_REQUEST);
}

{
    "status": 400,
    "message": "Failed to convert value of type 'java.lang.String' to required type 'int'; nested exception is java.lang.NumberFormatException: For input string: \"1000000000000000\"",
    "timeStamp": 1553501045234
}

<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-databind</artifactId>
  <version>[2.9.8,)</version>
</dependency>