读取文件工具类

import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.InputStreamReader;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URISyntaxException;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.util.Properties;

/**
 * Created by luopiao on 17-2-28.
 */
public abstract class ResourceUtils {

    private static final Logger logger = LoggerFactory.getLogger(ResourceUtils.class);

    public static final String CLASSPATH_URL_PREFIX = "classpath:";


    public static final String URL_PROTOCOL_FILE = "file";

    /**
     * URL protocol for an entry from a jar file: "jar"
     */
    public static final String URL_PROTOCOL_JAR = "jar";

    /**
     * URL protocol for an entry from a zip file: "zip"
     */
    public static final String URL_PROTOCOL_ZIP = "zip";

    /**
     * URL protocol for an entry from a WebSphere jar file: "wsjar"
     */
    public static final String URL_PROTOCOL_WSJAR = "wsjar";

    /**
     * URL protocol for an entry from a JBoss jar file: "vfszip"
     */
    public static final String URL_PROTOCOL_VFSZIP = "vfszip";

    /**
     * URL protocol for a JBoss file system resource: "vfsfile"
     */
    public static final String URL_PROTOCOL_VFSFILE = "vfsfile";

    /**
     * URL protocol for a general JBoss VFS resource: "vfs"
     */
    public static final String URL_PROTOCOL_VFS = "vfs";

    /**
     * File extension for a regular jar file: ".jar"
     */
    public static final String JAR_FILE_EXTENSION = ".jar";


    public static boolean isUrl(String resourceLocation) {
        if (resourceLocation == null) {
            return false;
        }
        if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
            return true;
        }
        try {
            new URL(resourceLocation);
            return true;
        } catch (MalformedURLException ex) {
            return false;
        }
    }


    public static URL getURL(String resourceLocation) {
        if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
            String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length());
            ClassLoader cl = ClassUtils.getDefaultClassLoader();
            URL url = (cl != null ? cl.getResource(path) : ClassLoader.getSystemResource(path));
            if (url == null) {
                String description = "class path resource [" + path + "]";
                throw new RuntimeException(description + " cannot be resolved to URL because it does not exist");
            }
            return url;
        }
        try {
            // try URL
            return new URL(resourceLocation);
        } catch (MalformedURLException ex) {
            logger.debug("no URL -> treat as file path");
            try {
                return new File(resourceLocation).toURI().toURL();
            } catch (MalformedURLException ex2) {
                throw new RuntimeException("Resource location [" + resourceLocation + "] is neither a URL not a well-formed file path");
            }
        }
    }


    public static File getFile(String resourceLocation) {
        if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) {
            String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length());
            String description = "class path resource [" + path + "]";
            ClassLoader cl = ClassUtils.getDefaultClassLoader();
            URL url = (cl != null ? cl.getResource(path) : ClassLoader.getSystemResource(path));
            if (url == null) {
                throw new RuntimeException(description +
                        " cannot be resolved to absolute file path because it does not exist");
            }
            return getFile(url, description);
        }
        try {
            // try URL
            return getFile(new URL(resourceLocation));
        } catch (MalformedURLException ex) {
            // no URL -> treat as file path
            return new File(resourceLocation);
        }
    }

    public static File getFile(URL resourceUrl) {
        return getFile(resourceUrl, "URL");
    }


    public static File getFile(URL resourceUrl, String description) {
        if (!URL_PROTOCOL_FILE.equals(resourceUrl.getProtocol())) {
            throw new RuntimeException(description + " cannot be resolved to absolute file path " + "because it does not reside in the file system: " + resourceUrl);
        }
        try {
            return new File(toURI(resourceUrl).getSchemeSpecificPart());
        } catch (Exception ex) {
            // Fallback for URLs that are not valid URIs (should hardly ever happen).
            return new File(resourceUrl.getFile());
        }
    }

    /**
     * 判断url 是否是jar 路径
     *
     * @param url url
     * @return 是否是jar 路径
     */
    public static boolean isJarURL(URL url) {
        String protocol = url.getProtocol();
        return (URL_PROTOCOL_JAR.equals(protocol) || URL_PROTOCOL_ZIP.equals(protocol) ||
                URL_PROTOCOL_VFSZIP.equals(protocol) || URL_PROTOCOL_WSJAR.equals(protocol));
    }

    public static boolean isJarFileURL(URL url) {
        return (URL_PROTOCOL_FILE.equals(url.getProtocol()) &&
                url.getPath().toLowerCase().endsWith(JAR_FILE_EXTENSION));
    }

    public static boolean isFileURL(URL url) {
        String protocol = url.getProtocol();
        return (URL_PROTOCOL_FILE.equals(protocol) || URL_PROTOCOL_VFSFILE.equals(protocol) ||
                URL_PROTOCOL_VFS.equals(protocol));
    }

    public static URI toURI(URL url) {
        return toURI(url.toString());
    }

    public static URI toURI(String location) {

        try {
            return new URI(StringUtils.replace(location, " ", "%20"));
        } catch (URISyntaxException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 读取配置文件
     *
     * @param path 文件路径
     * @return 返回 Properties
     */
    public static Properties readProperties(String path) {
        Properties config = new Properties();
        try (InputStreamReader in = new InputStreamReader(getURL(path).openStream(), StandardCharsets.UTF_8.name())) {
            config.load(in);
        } catch (Exception e) {
            logger.warn("缺少 {} 文件", path);
        }
        return config;
    }

    /**
     * 检查文件时候存在
     *
     * @param resourceLocation 文件路径
     * @return 是否存在
     */
    public static boolean existsResource(String resourceLocation) {
        try {
            getURL(resourceLocation);
            return true;
        } catch (Exception e) {
            return false;
        }
    }


}