06_HttpEntity的使用

本文介绍了HTTP实体的使用方法及资源回收策略,包括字符串实体的创建、内容属性获取、内容转换为字符串和字节数组,以及如何合理管理流实体以避免资源泄漏。

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HttpEntity实体即可以使流也可以使字符串形式。

具体有什么用法看他的方法解释:

package com.scl.base;

import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.ParseException;
import org.apache.http.entity.StringEntity;
import org.apache.http.util.EntityUtils;

public class HttpClientDemo06 {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		try {
			HttpEntity entity = new StringEntity("这一个字符串实体", "UTF-8");
			//内容类型
			System.out.println(entity.getContentType());
			//内容的编码格式
			System.out.println(entity.getContentEncoding());
			//内容的长度
			System.out.println(entity.getContentLength());
			//把内容转成字符串
			System.out.println(EntityUtils.toString(entity));
			//内容转成字节数组
			System.out.println(EntityUtils.toByteArray(entity).length);
			//还有个直接获得流
			//entity.getContent();
		} catch (UnsupportedEncodingException e) {
			throw new RuntimeException(e);
		} catch (ParseException e) {
		} catch (IOException e) {
		}
		
		
	}

}

对于实体的资源使用完之后要适当的回收资源,特别是对于流实体:例子代码如下

public static void test() throws IllegalStateException, IOException{
		HttpResponse response = null;
		HttpEntity entity = response.getEntity();
		
		if(entity!=null){
			 
				InputStream is = entity.getContent();
				try{
					//做一些操作
				}finally{
					//最后别忘了关闭应该关闭的资源,适当的释放资源
					if(is != null){
						is.close();
					}
					//这个方法也可以把底层的流给关闭了
					EntityUtils.consume(entity);
					//下面是这方法的源码
					/*public static void consume(final HttpEntity entity) throws IOException {
				        if (entity == null) {
				            return;
				        }
				        if (entity.isStreaming()) {
				            InputStream instream = entity.getContent();
				            if (instream != null) {
				                instream.close();
				            }
				        }
				    }*/
				}
				
			 
		}


gazebo无法显示(能运行但里面是一片空白),如何解决 报错:robot@robot-virtual-machine:~/桌面/final_homework$ ros2 launch fishbot_description display_robot.launch.py [INFO] [launch]: All log files can be found below /home/robot/.ros/log/2025-06-24-00-20-49-599928-robot-virtual-machine-9501 [INFO] [launch]: Default logging verbosity is set to INFO [INFO] [gazebo-1]: process started with pid [9502] [INFO] [ros2-2]: process started with pid [9504] [INFO] [robot_state_publisher-3]: process started with pid [9506] [INFO] [joint_state_publisher_gui-4]: process started with pid [9508] [INFO] [rviz2-5]: process started with pid [9510] [rviz2-5] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [robot_state_publisher-3] [WARN] [1750695649.813319615] [robot_state_publisher]: No robot_description parameter, but command-line argument available. Assuming argument is name of URDF file. This backwards compatibility fallback will be removed in the future. [robot_state_publisher-3] [WARN] [1750695649.826852862] [kdl_parser]: The root link base_link has an inertia specified in the URDF, but KDL does not support a root link with an inertia. As a workaround, you can add an extra dummy link to your URDF. [robot_state_publisher-3] [INFO] [1750695649.827031936] [robot_state_publisher]: got segment base_link [robot_state_publisher-3] [INFO] [1750695649.827101073] [robot_state_publisher]: got segment imu_link [robot_state_publisher-3] [INFO] [1750695649.827120086] [robot_state_publisher]: got segment lidar_link [joint_state_publisher_gui-4] qt.qpa.plugin: Could not find the Qt platform plugin "wayland" in "" [gazebo-1] Gazebo multi-robot simulator, version 11.10.2 [gazebo-1] Copyright (C) 2012 Open Source Robotics Foundation. [gazebo-1] Released under the Apache 2 License. [gazebo-1] http://gazebosim.org [gazebo-1] [rviz2-5] [INFO] [1750695650.682274084] [rviz2]: Stereo is NOT SUPPORTED [rviz2-5] [INFO] [1750695650.682997533] [rviz2]: OpenGl version: 4.1 (GLSL 4.1) [gazebo-1] Gazebo multi-robot simulator, version 11.10.2 [gazebo-1] Copyright (C) 2012 Open Source Robotics Foundation. [gazebo-1] Released under the Apache 2 License. [gazebo-1] http://gazebosim.org [gazebo-1] [rviz2-5] [INFO] [1750695650.787656132] [rviz2]: Stereo is NOT SUPPORTED [rviz2-5] [ERROR] [1750695651.002030871] [rviz2]: PluginlibFactory: The plugin for class 'rviz_default_plugins/Imu' failed to load. Error: According to the loaded plugin descriptions the class rviz_default_plugins/Imu with base class type rviz_common::Display does not exist. Declared types are nav2_rviz_plugins/ParticleCloud rviz_default_plugins/AccelStamped rviz_default_plugins/Axes rviz_default_plugins/Camera rviz_default_plugins/DepthCloud rviz_default_plugins/Effort rviz_default_plugins/FluidPressure rviz_default_plugins/Grid rviz_default_plugins/GridCells rviz_default_plugins/Illuminance rviz_default_plugins/Image rviz_default_plugins/InteractiveMarkers rviz_default_plugins/LaserScan rviz_default_plugins/Map rviz_default_plugins/Marker rviz_default_plugins/MarkerArray rviz_default_plugins/Odometry rviz_default_plugins/Path rviz_default_plugins/PointCloud rviz_default_plugins/PointCloud2 rviz_default_plugins/PointStamped rviz_default_plugins/Polygon rviz_default_plugins/Pose rviz_default_plugins/PoseArray rviz_default_plugins/PoseWithCovariance rviz_default_plugins/Range rviz_default_plugins/RelativeHumidity rviz_default_plugins/RobotModel rviz_default_plugins/TF rviz_default_plugins/Temperature rviz_default_plugins/TwistStamped rviz_default_plugins/Wrench [joint_state_publisher_gui-4] [INFO] [1750695651.012208224] [joint_state_publisher_gui]: Waiting for robot_description to be published on the robot_description topic... [gazebo-1] [Wrn] [gazebo_ros_init.cpp:178] [gazebo-1] # # ####### ####### ### ##### ####### [gazebo-1] ## # # # # # # # # [gazebo-1] # # # # # # # # # [gazebo-1] # # # # # # # # ##### [gazebo-1] # # # # # # # # # [gazebo-1] # ## # # # # # # # [gazebo-1] # # ####### # ### ##### ####### [gazebo-1] [gazebo-1] This version of Gazebo, now called Gazebo classic, reaches end-of-life [gazebo-1] in January 2025. Users are highly encouraged to migrate to the new Gazebo [gazebo-1] using our migration guides (https://gazebosim.org/docs/latest/gazebo_classic_migration?utm_source=gazebo_ros_pkgs&utm_medium=cli) [gazebo-1] [gazebo-1] [joint_state_publisher_gui-4] [INFO] [1750695651.076499270] [joint_state_publisher_gui]: Centering [ros2-2] [INFO] [1750695651.294862637] [spawn_entity]: Spawn Entity started [ros2-2] [INFO] [1750695651.296018549] [spawn_entity]: Loading entity XML from file /home/robot/桌面/final_homework/install/fishbot_description/share/fishbot_description/urdf/first_robot.urdf [ros2-2] [INFO] [1750695651.298336590] [spawn_entity]: Waiting for service /spawn_entity, timeout = 30 [ros2-2] [INFO] [1750695651.299681322] [spawn_entity]: Waiting for service /spawn_entity [joint_state_publisher_gui-4] [INFO] [1750695651.411230857] [joint_state_publisher_gui]: Centering [gazebo-1] [Msg] Waiting for master. [gazebo-1] [Msg] Connected to gazebo master @ http://127.0.0.1:11345 [gazebo-1] [Msg] Publicized address: 192.168.150.128 [gazebo-1] [Wrn] [GuiIface.cc:120] Could not find the Qt platform plugin "wayland" in "" [gazebo-1] [Err] [InsertModelWidget.cc:403] Missing model.config for model "/home/robot/.gazebo/models/wpr_simulation2" [gazebo-1] context mismatch in svga_surface_destroy [gazebo-1] context mismatch in svga_surface_destroy [gazebo-1] [Wrn] [Publisher.cc:135] Queue limit reached for topic /gazebo/default/user_camera/pose, deleting message. This warning is printed only once. [ros2-2] [ERROR] [1750695681.462499528] [spawn_entity]: Service /spawn_entity unavailable. Was Gazebo started with GazeboRosFactory? [ros2-2] [ERROR] [1750695681.464526737] [spawn_entity]: Spawn service failed. Exiting. [ros2-2] [ros2run]: Process exited with failure 1 [ERROR] [ros2-2]: process has died [pid 9504, exit code 1, cmd 'ros2 run gazebo_ros spawn_entity.py -entity first_robot -file /home/robot/桌面/final_homework/install/fishbot_description/share/fishbot_description/urdf/first_robot.urdf']. 除此之外,imu也无法显示
最新发布
06-24
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