java Java 中的 Logger log()方法，示例

Java 中的 Logger log()方法，示例

原文:https://www . geesforgeks . org/logger-log-method-in-Java-with-examples/

的日志()方法用于记录消息。如果记录器当前为作为参数传递的给定消息级别启用，则创建相应的日志记录，并将其转发给所有注册的输出处理程序对象。但是在 logger 类中，根据传递给方法的参数，有七种不同的 log()方法。

log(Level level, String msg): This method is used to Log a message, with no arguments.only message will be written in logger Output. Syntax:

```java public void log(Level level, String msg)

```

参数:该方法接受两个参数级别，这是消息级别标识符之一，例如，严重和消息，这是字符串消息(或消息目录中的一个键)。

返回值:此方法不返回任何内容

程序 1: 方法日志(级别级别，字符串消息)

```java // Java program to demonstrate // Logger.log(Level level, String msg) method

import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// log messages using log(Level level, String msg)         logger.log(Level.INFO, "This is message 1");         logger.log(Level.WARNING, "This is message 2");     } } ```

输出
log(Level level, String msg, Object param1): This method is used to Log a message, with one object parameter.

语法:

```java public void log(Level level, String msg, Object param1)

```

参数:此方法接受三个参数级别，它是消息级别标识符之一，例如，严重、消息，它是字符串消息(或消息目录中的一个键)和参数 1 ，它是消息的参数

返回值:此方法不返回任何内容

程序 2: 方法日志(级别级别，字符串消息，对象参数 1)

```java // Java program to demonstrate // Logger.log(Level level, String msg, Object param1)

import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// log messages using         // log(Level level, String msg, Object param1)         logger.log(Level.INFO, "logging: {0} ", "message1");         logger.log(Level.SEVERE, "logging: {0} ", "message2");     } } ```

输出:
log(Level level, String msg, Object[] params): This method is used to Log a message, with an array of object arguments.

语法:

```java public void log(Level level, String msg, Object[] params)

```

参数:该方法接受三个参数级别，它是消息级别标识符之一，例如，严重，消息，它是字符串消息(或消息目录中的一个键)和参数 1 ，它是消息的参数数组

返回值:此方法不返回任何内容

程序 3: 方法日志(级别级别，字符串消息，对象[]参数 1)

```java // Java program to demonstrate // Logger.log(Level level, String msg, Object[] param1)

import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// log messages using         // log(Level level, String msg, Object[] param1)         logger.log(Level.INFO, "logging: {0} {1}",                    new Object[] { "parameter1", "parameter2" });         logger.log(Level.WARNING, "logging: {0} {1} {2}",                    new Object[] { "p1", "p2", "p3" });     } } ```

输出:
log(Level level, String msg, Throwable thrown): This method is used to Log a message, with associated Throwable information.

语法:

```java public void log(Level level, String msg, Throwable thrown)

```

参数:该方法接受三个参数级别，它是消息级别标识符之一，例如，严重，消息，它是字符串消息(或消息目录中的一个键)和抛出的，它是与日志消息相关联的可抛出的。

返回值:此方法不返回任何内容

程序 4: 方法日志(级别级别，字符串消息，可抛出)

```java // Java program to demonstrate // Logger.log(Level level, String msg, Throwable thrown)

import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// log messages using         // log(Level level, String msg, Throwable thrown)         logger.log(Level.SEVERE, "logging:",                    new RuntimeException("Error"));         logger.log(Level.WARNING, "logging: ",                    new Exception("Exception"));     } } ```

输出:
log(Level level, Throwable thrown, Supplier msgSupplier): This method is used to Log a lazily constructed message, with associated Throwable information.The message and the given Throwable are then stored in a LogRecord which is forwarded to all registered Output handlers.

语法:

```java public void log(Level level, Throwable thrown, Supplier msgSupplier)

```

参数:该方法接受三个参数级别，它是消息级别标识符之一，例如，SEVERE，抛出，它是与日志消息相关联的可抛出的，以及msgssupplier，它是一个函数，当被调用时，它产生所需的日志消息。

返回值:此方法不返回任何内容

程序 5: 方法日志(级别级别，可投掷，供应商 msgSupplier)

```java // Java program to demonstrate // Logger.log(Level level, Throwable thrown, Supplier msgSupplier)

import java.util.function.Supplier; import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// Create a supplier method         Supplier StrSupplier             = () -> new String("Logger logs");

// log messages using         // log(Level level, Throwable thrown, Supplier msgSupplier)         logger.log(Level.SEVERE,                    new RuntimeException("Error"),                    StrSupplier);     } } ```

输出:
log(Level level, Supplier msgSupplier): This method is used to Log a message, which is only to be constructed if the logging level is such that the message will actually be logged.

语法:

```java public void log(Level level, Supplier msgSupplier)

```

参数:该方法接受两个参数级别，它是消息级别标识符之一，例如，重度和 msgSupplier ，它是一个函数，当被调用时，产生所需的日志消息。

返回值:此方法不返回任何内容

程序 6: 方法日志(级别级别，供应商 msgSupplier)

```java // Java program to demonstrate // Logger.log(Level level, msgSupplier)

import java.util.function.Supplier; import java.util.logging.Level; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// Create a supplier method         Supplier StrSupplier             = () -> new String("Logger messages");

// log messages using         // log(Level level, Supplier msgSupplier)         logger.log(Level.SEVERE,                    StrSupplier);     } } ```

输出:
log(LogRecord record): This method is used to Log a LogRecord.Using logRecord we will log the info to logger Outputs.

语法:

```java public void log(LogRecord record)

```

参数:该方法接受一个参数记录，即待发布的日志记录。

返回值:此方法不返回任何内容

程序 7: 方法日志(日志记录记录)

```java // Java program to demonstrate // Logger.log(LogRecord record)

import java.util.logging.Level; import java.util.logging.LogRecord; import java.util.logging.Logger;

public class GFG {

public static void main(String[] args)     {

// Create a Logger         Logger logger             = Logger.getLogger(                 GFG.class.getName());

// create logRecords         LogRecord record1 = new LogRecord(Level.INFO,                                           "Msg 1");         LogRecord record2 = new LogRecord(Level.INFO,                                           "Msg 2");

// log messages using         // log(LogRecord record)         logger.log(record1);         logger.log(record2);     } } ```

输出: