纯java实现读写windows注册表代码详解编程语言

java有一些类库可以实现读写windows注册表的方法，但是下面的类没有引用任何现成的类库，是纯java实现的。

import java.lang.reflect.InvocationTargetException; 
import java.lang.reflect.Method; 
import java.util.HashMap; 
import java.util.Map; 
import java.util.ArrayList; 
import java.util.List; 
import java.util.prefs.Preferences; 
public class WinRegistry { 
public static final int HKEY_CURRENT_USER = 0x80000001; 
public static final int HKEY_LOCAL_MACHINE = 0x80000002; 
public static final int REG_SUCCESS = 0; 
public static final int REG_NOTFOUND = 2; 
public static final int REG_ACCESSDENIED = 5; 
private static final int KEY_ALL_ACCESS = 0xf003f; 
private static final int KEY_READ = 0x20019; 
private static Preferences userRoot = Preferences.userRoot(); 
private static Preferences systemRoot = Preferences.systemRoot(); 
private static Class<? extends Preferences> userClass = userRoot.getClass(); 
private static Method regOpenKey = null; 
private static Method regCloseKey = null; 
private static Method regQueryValueEx = null; 
private static Method regEnumValue = null; 
private static Method regQueryInfoKey = null; 
private static Method regEnumKeyEx = null; 
private static Method regCreateKeyEx = null; 
private static Method regSetValueEx = null; 
private static Method regDeleteKey = null; 
private static Method regDeleteValue = null; 
static { 
try { 
regOpenKey = userClass.getDeclaredMethod("WindowsRegOpenKey", 
new Class[] { int.class, byte[].class, int.class }); 
regOpenKey.setAccessible(true); 
regCloseKey = userClass.getDeclaredMethod("WindowsRegCloseKey", 
new Class[] { int.class }); 
regCloseKey.setAccessible(true); 
regQueryValueEx = userClass.getDeclaredMethod("WindowsRegQueryValueEx", 
new Class[] { int.class, byte[].class }); 
regQueryValueEx.setAccessible(true); 
regEnumValue = userClass.getDeclaredMethod("WindowsRegEnumValue", 
new Class[] { int.class, int.class, int.class }); 
regEnumValue.setAccessible(true); 
regQueryInfoKey = userClass.getDeclaredMethod("WindowsRegQueryInfoKey1", 
new Class[] { int.class }); 
regQueryInfoKey.setAccessible(true); 
regEnumKeyEx = userClass.getDeclaredMethod(   
"WindowsRegEnumKeyEx", new Class[] { int.class, int.class,   
int.class });   
regEnumKeyEx.setAccessible(true); 
regCreateKeyEx = userClass.getDeclaredMethod(   
"WindowsRegCreateKeyEx", new Class[] { int.class,   
byte[].class });   
regCreateKeyEx.setAccessible(true);   
regSetValueEx = userClass.getDeclaredMethod(   
"WindowsRegSetValueEx", new Class[] { int.class,   
byte[].class, byte[].class });   
regSetValueEx.setAccessible(true);  
regDeleteValue = userClass.getDeclaredMethod(   
"WindowsRegDeleteValue", new Class[] { int.class,   
byte[].class });   
regDeleteValue.setAccessible(true);  
regDeleteKey = userClass.getDeclaredMethod(   
"WindowsRegDeleteKey", new Class[] { int.class,   
byte[].class });   
regDeleteKey.setAccessible(true);  
} 
catch (Exception e) { 
e.printStackTrace(); 
} 
} 
private WinRegistry() {  } 
/** 
* Read a value from key and value name 
* @param hkey   HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE 
* @param key 
* @param valueName 
* @return the value 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static String readString(int hkey, String key, String valueName)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
if (hkey == HKEY_LOCAL_MACHINE) { 
return readString(systemRoot, hkey, key, valueName); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
return readString(userRoot, hkey, key, valueName); 
} 
else { 
throw new IllegalArgumentException("hkey=" + hkey); 
} 
} 
/** 
* Read value(s) and value name(s) form given key  
* @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE 
* @param key 
* @return the value name(s) plus the value(s) 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static Map<String, String> readStringValues(int hkey, String key)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
if (hkey == HKEY_LOCAL_MACHINE) { 
return readStringValues(systemRoot, hkey, key); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
return readStringValues(userRoot, hkey, key); 
} 
else { 
throw new IllegalArgumentException("hkey=" + hkey); 
} 
} 
/** 
* Read the value name(s) from a given key 
* @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE 
* @param key 
* @return the value name(s) 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static List<String> readStringSubKeys(int hkey, String key)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
if (hkey == HKEY_LOCAL_MACHINE) { 
return readStringSubKeys(systemRoot, hkey, key); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
return readStringSubKeys(userRoot, hkey, key); 
} 
else { 
throw new IllegalArgumentException("hkey=" + hkey); 
} 
} 
/** 
* Create a key 
* @param hkey  HKEY_CURRENT_USER/HKEY_LOCAL_MACHINE 
* @param key 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static void createKey(int hkey, String key)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int [] ret; 
if (hkey == HKEY_LOCAL_MACHINE) { 
ret = createKey(systemRoot, hkey, key); 
regCloseKey.invoke(systemRoot, new Object[] { new Integer(ret[0]) }); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
ret = createKey(userRoot, hkey, key); 
regCloseKey.invoke(userRoot, new Object[] { new Integer(ret[0]) }); 
} 
else { 
throw new IllegalArgumentException("hkey=" + hkey); 
} 
if (ret[1] != REG_SUCCESS) { 
throw new IllegalArgumentException("rc=" + ret[1] + "  key=" + key); 
} 
} 
/** 
* Write a value in a given key/value name 
* @param hkey 
* @param key 
* @param valueName 
* @param value 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static void writeStringValue 
(int hkey, String key, String valueName, String value)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
if (hkey == HKEY_LOCAL_MACHINE) { 
writeStringValue(systemRoot, hkey, key, valueName, value); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
writeStringValue(userRoot, hkey, key, valueName, value); 
} 
else { 
throw new IllegalArgumentException("hkey=" + hkey); 
} 
} 
/** 
* Delete a given key 
* @param hkey 
* @param key 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static void deleteKey(int hkey, String key)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int rc = -1; 
if (hkey == HKEY_LOCAL_MACHINE) { 
rc = deleteKey(systemRoot, hkey, key); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
rc = deleteKey(userRoot, hkey, key); 
} 
if (rc != REG_SUCCESS) { 
throw new IllegalArgumentException("rc=" + rc + "  key=" + key); 
} 
} 
/** 
* delete a value from a given key/value name 
* @param hkey 
* @param key 
* @param value 
* @throws IllegalArgumentException 
* @throws IllegalAccessException 
* @throws InvocationTargetException 
*/ 
public static void deleteValue(int hkey, String key, String value)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int rc = -1; 
if (hkey == HKEY_LOCAL_MACHINE) { 
rc = deleteValue(systemRoot, hkey, key, value); 
} 
else if (hkey == HKEY_CURRENT_USER) { 
rc = deleteValue(userRoot, hkey, key, value); 
} 
if (rc != REG_SUCCESS) { 
throw new IllegalArgumentException("rc=" + rc + "  key=" + key + "  value=" + value); 
} 
} 
// ===================== 
private static int deleteValue 
(Preferences root, int hkey, String key, String value) 
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int[] handles = (int[]) regOpenKey.invoke(root, new Object[] { 
new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) }); 
if (handles[1] != REG_SUCCESS) { 
return handles[1];  // can be REG_NOTFOUND, REG_ACCESSDENIED 
} 
int rc =((Integer) regDeleteValue.invoke(root,   
new Object[] {  
new Integer(handles[0]), toCstr(value)  
})).intValue(); 
regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) }); 
return rc; 
} 
private static int deleteKey(Preferences root, int hkey, String key)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int rc =((Integer) regDeleteKey.invoke(root,   
new Object[] { new Integer(hkey), toCstr(key) })).intValue(); 
return rc;  // can REG_NOTFOUND, REG_ACCESSDENIED, REG_SUCCESS 
} 
private static String readString(Preferences root, int hkey, String key, String value) 
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int[] handles = (int[]) regOpenKey.invoke(root, new Object[] { 
new Integer(hkey), toCstr(key), new Integer(KEY_READ) }); 
if (handles[1] != REG_SUCCESS) { 
return null;  
} 
byte[] valb = (byte[]) regQueryValueEx.invoke(root, new Object[] { 
new Integer(handles[0]), toCstr(value) }); 
regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) }); 
return (valb != null ? new String(valb).trim() : null); 
} 
private static Map<String,String> readStringValues 
(Preferences root, int hkey, String key) 
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
HashMap<String, String> results = new HashMap<String,String>(); 
int[] handles = (int[]) regOpenKey.invoke(root, new Object[] { 
new Integer(hkey), toCstr(key), new Integer(KEY_READ) }); 
if (handles[1] != REG_SUCCESS) { 
return null; 
} 
int[] info = (int[]) regQueryInfoKey.invoke(root, 
new Object[] { new Integer(handles[0]) }); 
int count = info[0]; // count   
int maxlen = info[3]; // value length max 
for(int index=0; index<count; index++)  { 
byte[] name = (byte[]) regEnumValue.invoke(root, new Object[] { 
new Integer 
(handles[0]), new Integer(index), new Integer(maxlen + 1)}); 
String value = readString(hkey, key, new String(name)); 
results.put(new String(name).trim(), value); 
} 
regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) }); 
return results; 
} 
private static List<String> readStringSubKeys 
(Preferences root, int hkey, String key) 
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
List<String> results = new ArrayList<String>(); 
int[] handles = (int[]) regOpenKey.invoke(root, new Object[] { 
new Integer(hkey), toCstr(key), new Integer(KEY_READ)  
}); 
if (handles[1] != REG_SUCCESS) { 
return null; 
} 
int[] info = (int[]) regQueryInfoKey.invoke(root, 
new Object[] { new Integer(handles[0]) }); 
int count  = info[0]; // Fix: info[2] was being used here with wrong results. Suggested by davenpcj, confirmed by Petrucio 
int maxlen = info[3]; // value length max 
for(int index=0; index<count; index++)  { 
byte[] name = (byte[]) regEnumKeyEx.invoke(root, new Object[] { 
new Integer 
(handles[0]), new Integer(index), new Integer(maxlen + 1) 
}); 
results.add(new String(name).trim()); 
} 
regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) }); 
return results; 
} 
private static int [] createKey(Preferences root, int hkey, String key) 
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
return  (int[]) regCreateKeyEx.invoke(root, 
new Object[] { new Integer(hkey), toCstr(key) }); 
} 
private static void writeStringValue  
(Preferences root, int hkey, String key, String valueName, String value)  
throws IllegalArgumentException, IllegalAccessException, 
InvocationTargetException  
{ 
int[] handles = (int[]) regOpenKey.invoke(root, new Object[] { 
new Integer(hkey), toCstr(key), new Integer(KEY_ALL_ACCESS) }); 
regSetValueEx.invoke(root,   
new Object[] {  
new Integer(handles[0]), toCstr(valueName), toCstr(value)  
});  
regCloseKey.invoke(root, new Object[] { new Integer(handles[0]) }); 
} 
// utility 
private static byte[] toCstr(String str) { 
byte[] result = new byte[str.length() + 1]; 
for (int i = 0; i < str.length(); i++) { 
result[i] = (byte) str.charAt(i); 
} 
result[str.length()] = 0; 
return result; 
} 
}

使用方法如下：

String value = WinRegistry.readString ( 
WinRegistry.HKEY_LOCAL_MACHINE,                             //HKEY 
"SOFTWARE//Microsoft//Windows NT//CurrentVersion",           //Key 
"ProductName");                                              //ValueName 
System.out.println("Windows Distribution = " + value);