实现代码如下：

public class change {

public static void main(String[] args) {

String QJstr="全角转半角ＤＡＯ";

String result=SBCchange(QJstr);

System.out.println(QJstr+"\n"+result);

}

public static final String SBCchange(String QJstr)

{

String outStr="";

String Tstr="";

byte[] b=null;

for(int i=0;i{

try

{

Tstr=QJstr.substring(i,i+1);

b=Tstr.getBytes("unicode");

}

catch(java.io.UnsupportedEncodingException e)

{

e.printStackTrace();

}

if (b[3]==-1)

{

b[2]=(byte)(b[2]+32);

b[3]=0;

try

{

outStr=outStr+new String(b,"unicode");

}

catch(java.io.UnsupportedEncodingException e)

{

e.printStackTrace();

}

}else outStr=outStr+Tstr;

}

return outStr;

}

}

public class Test {

public static void main(String[] args) {

String QJstr = "hello";

String QJstr1 = "ｈｅｈｅ";

String result = BQchange(QJstr);

String result1 = QBchange(QJstr1);

System.out.println(QJstr + "\n" + result);

System.out.println(QJstr1 + "\n" + result1);

}

// 半角转全角

public static final String BQchange(String QJstr) {

String outStr = "";

String Tstr = "";

byte[] b = null;

for (int i = 0; i< QJstr.length(); i++) {

try {

Tstr = QJstr.substring(i, i + 1);

b = Tstr.getBytes("unicode");

} catch (java.io.UnsupportedEncodingException e) {

e.printStackTrace();

}

if (b[3] != -1) {

b[2] = (byte) (b[2] - 32);

b[3] = -1;

try {

outStr = outStr + new String(b, "unicode");

} catch (java.io.UnsupportedEncodingException e) {

e.printStackTrace();

}

} else

outStr = outStr + Tstr;

}

return outStr;

}

// 全角转半角

public static final String QBchange(String QJstr) {

String outStr = "";

String Tstr = "";

byte[] b = null;

for (int i = 0; i< QJstr.length(); i++) {

try {

Tstr = QJstr.substring(i, i + 1);

b = Tstr.getBytes("unicode");

} catch (java.io.UnsupportedEncodingException e) {

e.printStackTrace();

}

if (b[3] == -1) {

b[2] = (byte) (b[2] + 32);

b[3] = 0;

try {

outStr = outStr + new String(b, "unicode");

} catch (java.io.UnsupportedEncodingException e) {

e.printStackTrace();

}

} else

outStr = outStr + Tstr;

}

return outStr;

}

}

/**/// /

// / 转全角的函数(SBC case)

// /

// /任意字符串

// /全角字符串

// /

// /全角空格为12288，半角空格为32

// /其他字符半角(33-126)与全角(65281-65374)的对应关系是：均相差65248

// /

public static String ToSBC(String input) {

// 半角转全角：

char[] c = input.toCharArray();

for (int i = 0; i< c.length; i++) {

if (c[i] == 32) {

c[i] = (char) 12288;

continue;

}

if (c[i]< 127)

c[i] = (char) (c[i] + 65248);

}

return new String(c);

}

/**/// /

// / 转半角的函数(DBC case)

// /

// /任意字符串

// /半角字符串

// /

// /全角空格为12288，半角空格为32

// /其他字符半角(33-126)与考试.大提示全角(65281-65374)的对应关系是：均相差65248

// /

public static String ToDBC(String input) {

char[] c = input.toCharArray();

for (int i = 0; i< c.length; i++) {

if (c[i] == 12288) {

c[i] = (char) 32;

continue;

}

if (c[i]> 65280&& c[i]< 65375)

c[i] = (char) (c[i] - 65248);

}

return new String(c);

}