Question

让我们说我在一个非常大的项目中工作，并注意到一条空的打印行，所以我假设有一个System.out.println（＆＃34;＆＃34;） ;位于代码中的某个位置。我将如何试图弄清楚它在哪里，只是在整个项目中搜索所有出现的System.out.println？

Answer 1

如果你正在使用Java 8+，Durian有一个StackDumper类，可以很容易地找到给定行的打印位置：

StackDumper.dumpWhenSysOutContains("SomeTrigger")

当＆＃34; SomeTrigger＆＃34;打印出来后，这将被转储到System.err：

+----------\
| Triggered by SomeTrigger
| at package.MyClass.myMethod(MyClass.java:62)
| (the rest of the stacktrace)
+----------/

对于你的情况（寻找一个空字符串），它有点复杂：

PrintStream sysOutClean = System.out;
StringPrinter sysOutReplacement = new StringPrinter(StringPrinter.stringsToLines(line -> {
    if (line.isEmpty()) {
        StackDumper.dump("Found empty line");
    }
    sysOutClean.println(line);
}));
System.setOut(sysOutReplacement.toPrintStream());

现在，如果有这样的事情：

System.out.println("ABC");
System.out.println("123");
System.out.println("");
System.out.println("DEF");

然后您的控制台将如下所示：

ABC
123
+----------\
| Found empty line
| at package.MyClass.myMethod(MyClass.java:62)
| (the rest of the stacktrace)
+----------/

DEF

Answer 2

您可以实现自己的PrintStream并使用System.setOut来替换默认的标准输出。然后在类中放入一个调试标记（如果打印一个空字符串），或者通过调用堆栈打印出方法名称（抛出并捕获异常并获取堆栈信息）。

Answer 3

这可能是由于某些库也存在，如果你觉得它只是因为System.out.println那么，

解决方案1： 下面的代码片段可以帮助您找到执行它的位置。

        import java.io.FileNotFoundException;
        import java.io.PrintStream;

        public class CustomPrintStream extends PrintStream {

        public CustomPrintStream(String fileName) throws FileNotFoundException {
            super(fileName);
        }

            @Override
            public void print(String s) {

                try{
                    if(s == null || s.equals("")){
                        throw new Exception("Invalid print message");
                    }
                    super.print(s);
                }catch(Exception e){
                    //TODO Change to your logger framework and leave it as same 
                    e.printStackTrace();
                }
            }

            public static void main(String[] args) {
                try {
 //TODO : Change to your favorite path and make sure mentioned
//file is available
                    CustomPrintStream customPrintStream = new CustomPrintStream
    ("/home/prem/Desktop/test.log");
                    System.setOut(customPrintStream);
                    System.out.println("");

                } catch (FileNotFoundException e) {
                    //TODO Change to your logger framework and leave it as same 
                    e.printStackTrace();
                }
            }
        }

解决方案2： 由于IDE可用，请从他们那里获得帮助。如果你正在使用eclipse 菜单 - ＆gt;搜索 - ＆gt;文件搜索 - ＆gt;放置System.out.println（“”）;包含搜索并搜索它。

我宁愿说不要在任何代码中使用System.out.println，您可以使用checkstyle并确信没有开发人员使用它们。

Answer 4

示例：

/** Control sysout prints */
public static void main(String[] arg) throws Exception {
     System.out.println("Default"); //print normally

     SysOutController.setSysOutLocationAddressor();
     System.out.println("With Address"); //prints with calling location, and on click location cursor directly focus when System.out.**() called

     SysOutController.ignoreSysout();
     System.out.println("Ignored"); //this line will never prints

     SysOutController.resetSysOut();
     System.out.println("Default"); //print normally as it is (reset)
}

只需调用以下类的方法，即可帮助开发人员控制sysout

import java.io.FileDescriptor;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintStream;

/** 
 * Class which controls System.out prints in console <br/>
 * this class will helps developers to control prints in console
 * @implSpec
 * <pre><code>
 * System.out.println("Default"); //print normally
 * 
 * SysOutController.setSysOutLocationAddressor();
 * System.out.println("With Address"); //prints with calling location
 * 
 * SysOutController.ignoreSysout();
 * System.out.println("Ignored"); //this line will never prints
 * 
 * SysOutController.resetSysOut();
 * System.out.println("Default"); //print normally as it is (reset)
 * </code></pre>
 * @author Dharmendrasinh Chudasama
 */
public class SysOutController {

    private static void setOut(OutputStream out){
        System.setOut(new PrintStream(out));
    }

    private static final OutputStream CONSOLE = new FileOutputStream(FileDescriptor.out);

    /**
     * Reset System.out.print* method
     * @author Dharmendrasinh Chudasama
     */
    public static void resetSysOut() { setOut(CONSOLE); }

    /**
     * System.out.print* will not print anything in console
     * @author Dharmendrasinh Chudasama
     */
    public static void ignoreSysout() {
        setOut(new OutputStream() {
            @Override public void write(int b) throws IOException {}
        });
    }

    /**
     * Address/location of calling System.out.* method will append in console
     * @author Dharmendrasinh Chudasama
     */
    public static void setSysOutLocationAddressor() {
        setOut(new OutputStream() {
            @Override
            public void write(int b) throws IOException {
                if(b=='\n'){ //if newLine
                    final StackTraceElement callerStEl = new Throwable().getStackTrace()[9];
                    String pathData =
                        "\u001B[37m"    //low-visibality
                        + "\t :: ("+callerStEl.getFileName()+":"+callerStEl.getLineNumber()+") ["+callerStEl+"]"  //code path
                        + "\u001B[0m ";  //reset
                    CONSOLE.write(pathData.getBytes());

                }

                CONSOLE.write(b);
            }
        });
    }
}

Answer 5

定义一个类NewPrintStream扩展PrintStream

import java.io.FileNotFoundException;
import java.io.PrintStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class NewPrintStream extends PrintStream {
  private static final Logger LOGGER = LoggerFactory.getLogger(NewPrintStream.class);

  public NewPrintStream(String fileName) throws FileNotFoundException {
    super(fileName);
  }

  @Override
  public void println(String x) {
    LOGGER.info("xxxxxxx", new Exception("xxxx"));
  }
}

然后在主类中设置stdout / stderr打印流

System.setOut(new NewPrintStream("aaa"));
System.setErr(new NewPrintStream("aaa"));

Answer 6

在条件PrintStream.println(String x)或任何字符串中将条件断点放在x.equals("")中。

在system.out.println的代码中找到位置

6 个答案: