(1) 向HDFS中上传任意文本文件,如果指定的文件在HDFS中已经存在,由用户指定是追加到原有文件末尾还是覆盖原有的文件;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_1_ExistAppendCopy {
/**
* 判断路径是否存在
*/
public static boolean test(Configuration conf, String path) throws IOException {
FileSystem fs = FileSystem.get(conf);
return fs.exists(new Path(path));
}
/**
* 复制文件到指定路径 若路径已存在,则进行覆盖
*/
public static void copyFromLocalFile(Configuration conf, String localFilePath, String
remoteFilePath)
throws IOException {
FileSystem fs = FileSystem.get(conf);
Path localPath = new Path(localFilePath);
Path remotePath = new Path(remoteFilePath);
// fs.copyFromLocalFile 第一个参数表示是否删除源文件,第二个参数表示是否覆盖
fs.copyFromLocalFile(false, true, localPath, remotePath);
fs.close();
}
/**
* 追加文件内容
*/
public static void appendToFile(Configuration conf, String localFilePath, String
remoteFilePath)
throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
/* 创建一个文件读入流 */
FileInputStream in = new FileInputStream(localFilePath);
/* 创建一个文件输出流,输出的内容将追加到文件末尾 */
FSDataOutputStream out = fs.append(remotePath);
/* 读写文件内容 */
byte[] data = new byte[1024];
int read = -1;
while ((read = in.read(data)) > 0) {
out.write(data, 0, read);
}
out.close();
in.close();
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String localFilePath = "/usr/local/hadoop/input/append.txt"; // 本地路径
String remoteFilePath = "/user/hadoop/data3merge.txt"; // HDFS 路径
String choice = "append"; // 若文件存在则追加到文件末尾
// String choice = "overwrite"; // 若文件存在则覆盖
try {
/* 判断文件是否存在 */
Boolean fileExists = false;
if (HW1_1_ExistAppendCopy.test(conf, remoteFilePath)) {
fileExists = true;
System.out.println(remoteFilePath + " 已存在.");
} else {
System.out.println(remoteFilePath + " 不存在.");
}
/* 进行处理 */
if (!fileExists) { // 文件不存在,则上传
HW1_1_ExistAppendCopy.copyFromLocalFile(conf, localFilePath,
remoteFilePath);
System.out.println(localFilePath + " 已上传至 " + remoteFilePath);
} else if (choice.equals("overwrite")) { // 选择覆盖
HW1_1_ExistAppendCopy.copyFromLocalFile(conf, localFilePath,
remoteFilePath);
System.out.println(localFilePath + " 已覆盖 " + remoteFilePath);
} else if (choice.equals("append")) { // 选择追加
HW1_1_ExistAppendCopy.appendToFile(conf, localFilePath, remoteFilePath);
System.out.println(localFilePath + " 已追加至 " + remoteFilePath);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(2) 从HDFS中下载指定文件,如果本地文件与要下载的文件名称相同,则自动对下载的文件重命名;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_2_ExistRenameCopy {
/**
* 下载文件到本地 判断本地路径是否已存在,若已存在,则自动进行重命名
*/
public static void copyToLocal(Configuration conf, String remoteFilePath, String localFilePath)
throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
File f = new File(localFilePath);
/* 如果文件名存在,自动重命名(在文件名后面加上 _0, _1 ...) */
if (f.exists()) {
System.out.println(localFilePath + " 已存在.");
Integer i = 0;
while (true) {
f = new File(localFilePath + "_" + i.toString());
if (!f.exists()) {
localFilePath = localFilePath + "_" + i.toString();
break;
}
}
System.out.println("将重新命名为: " + localFilePath);
}
// 下载文件到本地
Path localPath = new Path(localFilePath);
fs.copyToLocalFile(remotePath, localPath);
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String localFilePath = "/usr/local/hadoop/output/data3merge.txt"; // 本地路径
String remoteFilePath = "/user/hadoop/data3merge.txt"; // HDFS 路径
try {
HW1_2_ExistRenameCopy.copyToLocal(conf, remoteFilePath, localFilePath);
System.out.println("下载完成");
} catch (Exception e) {
e.printStackTrace();
}
}
}
(3) 将HDFS中指定文件的内容输出到终端中;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_3_CatFile {
/**
* 读取文件内容
*/
public static void cat(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
FSDataInputStream in = fs.open(remotePath);
BufferedReader d = new BufferedReader(new InputStreamReader(in));
String line = null;
while ((line = d.readLine()) != null)
System.out.println(line);
d.close();
in.close();
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteFilePath = "/user/hadoop/data3merge.txt"; // HDFS 路径
try {
System.out.println("读取文件: " + remoteFilePath);
HW1_3_CatFile.cat(conf, remoteFilePath);
System.out.println("\n 读取完成");
} catch (Exception e) {
e.printStackTrace();
}
}
}
(4) 显示HDFS中指定的文件的读写权限、大小、创建时间、路径等信息;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
import java.text.SimpleDateFormat;
public class HW1_4_ShowMsg {
/**
* 显示指定文件的信息
*/
public static void ls(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
FileStatus[] fileStatuses = fs.listStatus(remotePath);
for (FileStatus s : fileStatuses) {
System.out.println("路径: " + s.getPath().toString());
System.out.println("权限: " + s.getPermission().toString());
System.out.println("大小: " + s.getLen());
/* 返回的是时间戳,转化为时间日期格式 */
Long timeStamp = s.getModificationTime();
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date = format.format(timeStamp);
System.out.println("时间: " + date);
}
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteFilePath = "/user/hadoop/data3merge.txt"; // HDFS 路径
try {
System.out.println("读取文件信息: " + remoteFilePath);
HW1_4_ShowMsg.ls(conf, remoteFilePath);
System.out.println("\n 读取完成");
} catch (Exception e) {
e.printStackTrace();
}
}
}
(5) 给定HDFS中某一个目录,输出该目录下的所有文件的读写权限、大小、创建时间、路径等信息,如果该文件是目录,则递归输出该目录下所有文件相关信息;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
import java.text.SimpleDateFormat;
public class HW1_5_ShowAllMsg {
/**
* 显示指定文件夹下所有文件的信息(递归)
*/
public static void lsDir(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
/* 递归获取目录下的所有文件 */
RemoteIterator<LocatedFileStatus> remoteIterator = fs.listFiles(dirPath, true);
/* 输出每个文件的信息 */
while (remoteIterator.hasNext()) {
FileStatus s = remoteIterator.next();
System.out.println("路径: " + s.getPath().toString());
System.out.println("权限: " + s.getPermission().toString());
System.out.println("大小: " + s.getLen());
/* 返回的是时间戳,转化为时间日期格式 */
Long timeStamp = s.getModificationTime();
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String date = format.format(timeStamp);
System.out.println("时间: " + date);
System.out.println();
}
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteDir = "/user/hadoop"; // HDFS 路径
try {
System.out.println("(递归)读取目录下所有文件的信息: " + remoteDir);
HW1_5_ShowAllMsg.lsDir(conf, remoteDir);
System.out.println("读取完成");
} catch (Exception e) {
e.printStackTrace();
}
}
}
(6) 提供一个HDFS内的文件的路径,对该文件进行创建和删除操作。如果文件所在目录不存在,则自动创建目录;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_6_CreateDelete {
/**
* 判断路径是否存在
*/
public static boolean test(Configuration conf, String path) throws IOException {
FileSystem fs = FileSystem.get(conf);
return fs.exists(new Path(path));
}
/**
* 创建目录
*/
public static boolean mkdir(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
boolean result = fs.mkdirs(dirPath);
fs.close();
return result;
}
/**
* 创建文件
*/
public static void touchz(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
FSDataOutputStream outputStream = fs.create(remotePath);
outputStream.close();
fs.close();
}
/**
* 删除文件
*/
public static boolean rm(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
boolean result = fs.delete(remotePath, false);
fs.close();
return result;
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteFilePath = "/user/hadoop/input_new/text.txt"; // HDFS 路径
String remoteDir = "/user/hadoop/input_new"; // HDFS 路径对应的目录
try {
/* 判断路径是否存在,存在则删除,否则进行创建 */
if (HW1_6_CreateDelete.test(conf, remoteFilePath)) {
HW1_6_CreateDelete.rm(conf, remoteFilePath); // 删除
System.out.println("删除路径: " + remoteFilePath);
} else {
if (!HW1_6_CreateDelete.test(conf, remoteDir)) { // 若目录不存在,则进行创建
HW1_6_CreateDelete.mkdir(conf, remoteDir);
System.out.println("创建文件夹: " + remoteDir);
}
HW1_6_CreateDelete.touchz(conf, remoteFilePath);
System.out.println("创建路径: " + remoteFilePath);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(7) 提供一个HDFS的目录的路径,对该目录进行创建和删除操作。创建目录时,如果目录文件所在目录不存在则自动创建相应目录;删除目录时,由用户指定当该目录不为空时是否还删除该目录;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_7_CreateDeleteDir {
/**
* 判断路径是否存在 s
*/
public static boolean test(Configuration conf, String path) throws IOException {
FileSystem fs = FileSystem.get(conf);
return fs.exists(new Path(path));
}
/**
* 判断目录是否为空 true: 空,false: 非空
*/
public static boolean isDirEmpty(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
RemoteIterator<LocatedFileStatus> remoteIterator = fs.listFiles(dirPath, true);
return !remoteIterator.hasNext();
}
/**
* 创建目录
*/
public static boolean mkdir(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
boolean result = fs.mkdirs(dirPath);
fs.close();
return result;
}
/**
* 删除目录
*/
public static boolean rmDir(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
/* 第二个参数表示是否递归删除所有文件 */
boolean result = fs.delete(dirPath, true);
fs.close();
return result;
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteDir = "/user/hadoop/input_new/input_bk"; // HDFS 目录
Boolean forceDelete = false; // 是否强制删除
try {
/* 判断目录是否存在,不存在则创建,存在则删除 */
if (!HW1_7_CreateDeleteDir.test(conf, remoteDir)) {
HW1_7_CreateDeleteDir.mkdir(conf, remoteDir); // 创建目录
System.out.println("创建目录: " + remoteDir);
} else {
if (HW1_7_CreateDeleteDir.isDirEmpty(conf, remoteDir) || forceDelete) { // 目录为空或强制删除
HW1_7_CreateDeleteDir.rmDir(conf, remoteDir);
System.out.println("删除目录: " + remoteDir);
} else { // 目录不为空
System.out.println("目录不为空,不删除: " + remoteDir);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(8) 向HDFS中指定的文件追加内容,由用户指定内容追加到原有文件的开头或结尾;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_8_AppendInsert {
/**
* 判断路径是否存在
*/
public static boolean test(Configuration conf, String path) throws IOException {
FileSystem fs = FileSystem.get(conf);
return fs.exists(new Path(path));
}
/**
* 追加文本内容
*/
public static void appendContentToFile(Configuration conf, String content, String
remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
/* 创建一个文件输出流,输出的内容将追加到文件末尾 */
FSDataOutputStream out = fs.append(remotePath);
out.write(content.getBytes());
out.close();
fs.close();
}
/**
* 追加文件内容
*/
public static void appendToFile(Configuration conf, String localFilePath, String
remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
/* 创建一个文件读入流 */
FileInputStream in = new FileInputStream(localFilePath);
/* 创建一个文件输出流,输出的内容将追加到文件末尾 */
FSDataOutputStream out = fs.append(remotePath);
/* 读写文件内容 */
byte[] data = new byte[1024];
int read = -1;
while ( (read = in.read(data)) > 0 ) {
out.write(data, 0, read);
}
out.close();
in.close();
fs.close();
}
/**
* 移动文件到本地
* 移动后,删除源文件
*/
public static void moveToLocalFile(Configuration conf, String remoteFilePath, String
localFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
Path localPath = new Path(localFilePath);
fs.moveToLocalFile(remotePath, localPath);
}
/**
* 创建文件
*/
public static void touchz(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
FSDataOutputStream outputStream = fs.create(remotePath);
outputStream.close();
fs.close();
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name","hdfs://localhost:9000");
String remoteFilePath = "/user/hadoop/append_ch.txt"; // HDFS 文件
String content = "新追加的内容\n";
String choice = "after"; //追加到文件末尾
// String choice = "before"; // 追加到文件开头
try {
/* 判断文件是否存在 */
if ( !HW1_8_AppendInsert.test(conf, remoteFilePath) ) {
System.out.println("文件不存在: " + remoteFilePath);
} else {
if ( choice.equals("after") ) { // 追加在文件末尾
HW1_8_AppendInsert.appendContentToFile(conf, content,
remoteFilePath);
System.out.println("已追加内容到文件末尾" + remoteFilePath);
} else if ( choice.equals("before") ) { // 追加到文件开头
/* 没有相应的 api 可以直接操作,因此先把文件移动到本地,创建一个
新的 HDFS,再按顺序追加内容 */
String localTmpPath = "/usr/local/hadoop/input/append.txt";
HW1_8_AppendInsert.moveToLocalFile(conf, remoteFilePath,
localTmpPath); // 移动到本地
HW1_8_AppendInsert.touchz(conf, remoteFilePath); // 创建一个新文件
HW1_8_AppendInsert.appendContentToFile(conf, content,
remoteFilePath); // 先写入新内容
HW1_8_AppendInsert.appendToFile(conf, localTmpPath, remoteFilePath);
// 再写入原来内容
System.out.println("已追加内容到文件开头: " + remoteFilePath);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(9) 删除HDFS中指定的文件;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_9_DeleteFile {
/**
* 删除文件
*/
public static boolean rm(Configuration conf, String remoteFilePath) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path remotePath = new Path(remoteFilePath);
boolean result = fs.delete(remotePath, false);
fs.close();
return result;
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name","hdfs://localhost:9000");
String remoteFilePath = "/user/hadoop/data3merge.txt"; // HDFS 文件
try {
if ( HW1_9_DeleteFile.rm(conf, remoteFilePath) ) {
System.out.println("文件删除: " + remoteFilePath);
} else {
System.out.println("操作失败(文件不存在或删除失败)");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(10) 删除HDFS中指定的目录,由用户指定目录中如果存在文件时是否删除目录;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_10_DeleteDir {
/**
* 判断目录是否为空
* true: 空,false: 非空
*/
public static boolean isDirEmpty(Configuration conf, String remoteDir) throws IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
RemoteIterator<LocatedFileStatus> remoteIterator = fs.listFiles(dirPath, true);
return !remoteIterator.hasNext();
}
/**
* 删除目录
*/
public static boolean rmDir(Configuration conf, String remoteDir, boolean recursive) throws
IOException {
FileSystem fs = FileSystem.get(conf);
Path dirPath = new Path(remoteDir);
/* 第二个参数表示是否递归删除所有文件 */
boolean result = fs.delete(dirPath, recursive);
fs.close();
return result;
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name","hdfs://localhost:9000");
String remoteDir = "/user/hadoop/input_new/input_bk"; // HDFS 目录
Boolean forceDelete = false; // 是否强制删除
try {
if ( !HW1_10_DeleteDir.isDirEmpty(conf, remoteDir) && !forceDelete ) {
System.out.println("目录不为空,不删除");
} else {
if ( HW1_10_DeleteDir.rmDir(conf, remoteDir, forceDelete) ) {
System.out.println("目录已删除: " + remoteDir);
} else {
System.out.println("操作失败");
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
(11) 在HDFS中,将文件从源路径移动到目的路径。
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.*;
import java.io.*;
public class HW1_11_MVFile {
/**
* 移动文件
*/
public static boolean mv(Configuration conf, String remoteFilePath, String remoteToFilePath)
throws IOException {
FileSystem fs = FileSystem.get(conf);
Path srcPath = new Path(remoteFilePath);
Path dstPath = new Path(remoteToFilePath);
boolean result = fs.rename(srcPath, dstPath);
fs.close();
return result;
}
/**
* 主函数
*/
public static void main(String[] args) {
Configuration conf = new Configuration();
conf.set("fs.default.name", "hdfs://localhost:9000");
String remoteFilePath = "hdfs:///user/hadoop/append_ch.txt"; // 源文件 HDFS 路径
String remoteToFilePath = "hdfs:///user/hadoop/output.txt"; // 目的 HDFS 路径
try {
if (HW1_11_MVFile.mv(conf, remoteFilePath, remoteToFilePath)) {
System.out.println("将文件 " + remoteFilePath + " 移动到 " +
remoteToFilePath);
} else {
System.out.println("操作失败(源文件不存在或移动失败)");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}