Properties文件工具类的使用--获取所有的键值、删除键、更新键等操作

　　有时候我们希望处理properties文件，properties文件是键值对的文件形式，我们可以借助Properties类操作。

工具类如下:(代码中日志采用了slf4j日志)

package cn.xm.exam.utils;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.Map.Entry;

import java.util.Properties;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 * 操作properties文件的工具类(此工具类的file都是src目录下的properties文件，编译之后在build目录下)

 *

 * @author QiaoLiQiang

 * @time 2018年11月3日下午12:05:32

 */

public class PropertiesFileUtils {

    private static final Logger log = LoggerFactory.getLogger(PropertiesFileUtils.class);

    /**

     * 构造函数私有化

     */

    private PropertiesFileUtils() {

    }

    /**

     * 保存或更新properties文件中的key

     *

     * @param fileName

     * @param key

     * @param value

     */

    public static void saveOrUpdateProperty(String fileName, String key, String value) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            String path = ResourcesUtil.class.getClassLoader().getResource(fileName).getPath();

            log.debug("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            properties.setProperty(key, value);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @param key

     * @return

     */

    public static String getPropertyValue(String fileName, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        String value = "";

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            value = properties.getProperty(key);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return value;

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @return

     */

    public static Properties getProperties(String fileName) {

        Properties properties = new Properties();

        InputStream inputStream;

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @return

     */

    public static Properties removeProperty(String fileName, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            log.info("properties -> {}", properties);

            if (properties != null && properties.containsKey(key)) {

                log.info("remove key:{}", key);

                properties.remove(key);

            }

            // 保存到文件中(将properties保存到文件)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

    public static void main(String[] args) {

        // 保存三个 最后一个相当于更新

        PropertiesFileUtils.saveOrUpdateProperty("settings.properties", "a", "aaa");

        PropertiesFileUtils.saveOrUpdateProperty("settings.properties", "b", "bbb");

        PropertiesFileUtils.saveOrUpdateProperty("settings.properties", "c", "ccc");

        PropertiesFileUtils.saveOrUpdateProperty("settings.properties", "a", "AAA");

        // 获取所有的properties

        Properties properties = PropertiesFileUtils.getProperties("settings.properties");

        System.out.println(properties);

        // 删除a

        PropertiesFileUtils.removeProperty("settings.properties", "a");

        // 获取所有的properties

        Properties properties1 = PropertiesFileUtils.getProperties("settings.properties");

        System.out.println(properties1);

    }

}

结果:

{b=bbb, a=AAA, c=ccc}
{b=bbb, c=ccc}

解释:

Properties是继承了HashTable的一个普通类，所以我们可以简单的认为操作Properties就是在操作HashTable。

public

class Properties extends Hashtable<Object,Object> {

     private static final long serialVersionUID = 4112578634029874840L;

    protected Properties defaults;

。。。

}

 由于HasTable键不可以重复，所以我们在saveOrUpdateProperty中直接setProperty的时候如果没有key会创建key，如果key存在会覆盖原来的值。

　　properties.load(inputStream);是将properties文件中的key=value的数据加载到properties中;

　　properties.store(outputStream, "");是将properties保存到一个文件中。

补充:上面代码还可以进一步将properties文件的位置封装全路径:

package cn.xm.exam.utils;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.Properties;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

/**

 *

 * @author QiaoLiQiang

 * @time 2018年11月3日下午12:05:32

 */

public class PropertiesFileUtils {

    private static final Logger log = LoggerFactory.getLogger(PropertiesFileUtils.class);

    /**

     * 构造函数私有化

     */

    private PropertiesFileUtils() {

    }

    /**

     * 保存或更新properties文件中的key

     *

     * @param fileName

     * @param key

     * @param value

     */

    public static void saveOrUpdateProperty(String fileName, String key, String value) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            String path = ResourcesUtil.class.getClassLoader().getResource(fileName).getPath();

            log.debug("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            properties.setProperty(key, value);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @param key

     * @return

     */

    public static String getPropertyValue(String fileName, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        String value = "";

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            value = properties.getProperty(key);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return value;

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @return

     */

    public static Properties getProperties(String fileName) {

        Properties properties = new Properties();

        InputStream inputStream;

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

    /**

     * 获取Properties

     *

     * @param fileName

     * @return

     */

    public static Properties removeProperty(String fileName, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            String path = PropertiesFileUtils.class.getClassLoader().getResource(fileName).getPath();

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            log.info("properties -> {}", properties);

            if (properties != null && properties.containsKey(key)) {

                log.info("remove key:{}", key);

                properties.remove(key);

            }

            // 保存到文件中(将properties保存到文件)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

    /**

     * 保存或更新properties文件中的key

     *

     * @param path

     *            文件全路径

     * @param key

     * @param value

     */

    public static void saveOrUpdatePropertyByFilePath(String path, String key, String value) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            log.debug("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            properties.setProperty(key, value);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

    }

    /**

     * 获取Properties

     *

     * @param path

     *            文件全路径

     * @param key

     * @return

     */

    public static String getPropertyValueByFilePath(String path, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        String value = "";

        try {

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            value = properties.getProperty(key);

            // 保存到文件中(如果有的话会自动更新，没有会创建)

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return value;

    }

    /**

     * 获取Properties

     *

     * @param path

     *            文件全路径

     * @return

     */

    public static Properties getPropertiesByFilePath(String path) {

        Properties properties = new Properties();

        InputStream inputStream;

        try {

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

    /**

     * 获取Properties

     *

     * @param path

     *            文件全路径

     * @param key

     *            key值

     * @return

     */

    public static Properties removePropertyByFilePath(String path, String key) {

        Properties properties = new Properties();

        InputStream inputStream;

        OutputStream outputStream;

        try {

            log.info("path -> {}", path);

            inputStream = new FileInputStream(new File(path));

            properties.load(inputStream);

            log.info("properties -> {}", properties);

            if (properties != null && properties.containsKey(key)) {

                log.info("remove key:{}", key);

                properties.remove(key);

            }

            // 保存到文件中(将properties保存到文件)

            outputStream = new FileOutputStream(new File(path));

            properties.store(outputStream, "");

            outputStream.close();

            inputStream.close();

        } catch (FileNotFoundException e) {

            log.error("saveOrUpdateProperty error", e);

        } catch (IOException e) {

            log.error("saveOrUpdateProperty error", e);

        }

        return properties;

    }

}

补充：如果是spring项目读取jar包中的配置可以用 ClassPathResource 进行读取:

    /**

     * 获取文件中对应的key的名称

     *

     * @param fileName

     * @param key

     * @return

     */

    public static String getPropertyValue(String fileName, String key) {

        Properties properties = new Properties();

        InputStream inputStream = null;

        String value = "";

        try {

            ClassPathResource resource = new ClassPathResource(fileName);

            inputStream = resource.getInputStream();

            properties.load(inputStream);

            value = properties.getProperty(key);

        } catch (Exception e) {

            log.error("saveOrUpdateProperty error", e);

        } finally {

            IOUtils.closeQuietly(inputStream);

        }

        return value;

    }

补充：由于springboot打成jar包之后里面的文件不能实时修改，所以在当前程序的主目录下创建一settings.properties文件进行操作

package cn.qs.utils.system;

import java.io.File;

import java.io.IOException;

import java.util.Date;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.io.FileUtils;

import org.apache.commons.lang3.StringUtils;

import org.apache.commons.lang3.SystemUtils;

import org.apache.commons.lang3.time.DateFormatUtils;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.web.context.request.RequestContextHolder;

import org.springframework.web.context.request.ServletRequestAttributes;

import cn.qs.bean.user.User;

import cn.qs.utils.UUIDUtils;

import cn.qs.utils.file.PropertiesFileUtils;

public class MySystemUtils {

    private static final Logger LOGGER = LoggerFactory.getLogger(MySystemUtils.class);

    static {

        checkSettingPropertyFiles();

    }

    private MySystemUtils() {

    }

    /**

     * 检查settings.properties文件是否存在，不存在就创建

     */

    public static void checkSettingPropertyFiles() {

        File userDir = SystemUtils.getUserDir();

        File propertiesFile = new File(userDir, "settings.properties");

        if (!propertiesFile.exists()) {

            try {

                propertiesFile.createNewFile();

                LOGGER.info("create settings.properties success, path: {}", propertiesFile.getAbsolutePath());

            } catch (IOException e) {

                LOGGER.error("create settings.properties failed", e);

            }

        }

    }

    public static final String settings_file_path = SystemUtils.getUserDir().getAbsolutePath() + "/settings.properties";

    public static String getProductName() {

        return getProperty("productName", "管理网");

    }

    public static String getProperty(String key) {

        return getProperty(key, "");

    }

    public static String getProperty(String key, String defaultValue) {

        return StringUtils.defaultIfBlank(PropertiesFileUtils.getPropertyValueByFilePath(settings_file_path, key),

                defaultValue);

    }

    public static void setProperty(String key, Object value) {

        PropertiesFileUtils.saveOrUpdatePropertyByFilePath(settings_file_path, key, String.valueOf(value));

    }

}

　　SystemUtils.getUserDir()方法获取的是项目所在的路径，如果是springboot打的jar包是jar包所在的目录。

Properties文件工具类的使用--获取所有的键值、删除键、更新键等操作的相关教程结束。