Java的异常处理体系详解

public int foo() {
    try {
        // some code that may throw an exception
        return 1;
    } catch (Exception e) {
        // handle exception
        return 2;
    } finally {
        return 3;
    }
}

//读取文本文件的内容  BufferedReader 需要在使用完毕后手动释放资源
public static void main(String[] args) {
        String fileName = "C:\\Users\\Administrator\\Desktop\\数据分片.txt";
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new FileReader(fileName))
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line); // 处理每一行的内容
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }


//读取文本文件的内容  BufferedReader 在使用完毕后自动释放资源 (Java 7 之后支持try-with-resources )
public static void main(String[] args) {
        String fileName = "C:\\Users\\Administrator\\Desktop\\数据分片.txt";
        try (BufferedReader reader = new BufferedReader(new FileReader(fileName))) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line); // 处理每一行的内容
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


//读取文本文件的内容  如果有多个资源同时声明 可以使用分号分隔即可
public static void main(String[] args) {
        String fileName = "C:\\Users\\Administrator\\Desktop\\数据分片.txt";
        try (BufferedReader reader = new BufferedReader(new FileReader(fileName)); Scanner scanner = new Scanner(new File(fileName));) {
            String line;
            while ((line = reader.readLine()) != null) {
                System.out.println(line); // 处理每一行的内容
            }

            System.out.println("=====>>>>>>>>>>>>>>>>>>>>>>>>");
            while (scanner.hasNext()) {
                System.out.println(scanner.nextLine()); // 处理每一行的内容
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }

public void aa() {
    try {
    int a = 1/0;
    } catch (Exception e) {
    // 这里一定要记录完整的异常信息
      log.error("哦，错误竟然发生了: {}" , e);
    }
}

/**
 * 自定义错误类型
 * */
public enum MyErrorCode {

    EMPTY_PARAM_ERROR("EMPTY_PARAM_ERROR", "远程调用错误"),
    REMOTE_ERROR("REMOTE_ERROR", "远程调用错误"),
    ;


    private final String code;
    private final String text;

    MyErrorCode(String code, String text) {
        this.code = code;
        this.text = text;
    }

    public String getText() {
        return text;
    }

    public String getCode() {
        return code;
    }

}

/**
 * 自定义异常
 * */
public class MyException extends RuntimeException {

    /**
     * 错误代码
     */
    private String errorCode;

    /**
     * 格式化异常参数
     */
    private List<String> paramList;

    /**
     * 最常用的方法
     * @param MyErrorCode 自定义错误代码
     */
    public MyException(MyErrorCode MyErrorCode) {
        this(MyErrorCode.getCode(), MyErrorCode.getText(), null);
    }

    public MyException(String errorCode, String message) {
        this(errorCode, message, null);
    }

    private MyException(String errorCode, String message, Throwable cause) {
        super(message, cause);
        this.errorCode = errorCode;
    }

    public MyException(MyErrorCode MyErrorCode, Throwable cause) {
        this(MyErrorCode.getCode(), MyErrorCode.getText(), cause);
    }

    public MyException(MyErrorCode MyErrorCode, List<String> params) {
        this(MyErrorCode.getCode(), MyErrorCode.getText(), null);
        this.paramList = params;
    }

    public List<String> getParamList() {
        return paramList;
    }

    public void setParamList(List<String> paramList) {
        this.paramList = paramList;
    }

    public String getErrorCode() {
        return this.errorCode;
    }
}

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;

import java.util.List;


@Slf4j
@RestControllerAdvice
public class MyExceptionHandle {


    @ExceptionHandler(MyException.class)
    public JsonResult<?> handleMyException(MyException e) {
        String message = e.getMessage();
        log.error("current web request error:" + message, e);
        JsonResult<Object> jsonResult = new JsonResult<>(false, message);
        String errorCode = e.getErrorCode();
        jsonResult.setErrCode(errorCode);
        List<String> paramList = e.getParamList();
        jsonResult.setData(paramList);
        return jsonResult;
    }


    /**
     * 处理未知异常
     *
     * @return JsonResult
     */
    @ExceptionHandler(Exception.class)
    private JsonResult<?> handleUnKnownException(Exception e) {
        if (null == e || StringUtils.isBlank(e.getMessage())) {
            log.error("current web request error:", e);
            return new JsonResult<Object>(false, "500", "unknownException", e);
        }
        String message = e.getMessage();
        log.error("current web request error:" + message, e);
        e.printStackTrace();
        JsonResult<Object> jsonResult = new JsonResult<>(false, "500", message, e);
        jsonResult.setMsg("unknownException");
        return jsonResult;
    }
}