http断点续传简单实现（java)

/* *fN+wiPD  
**SiteFileFetch.java 6A"$9sj6  
*/ oU=vl!\J  
package NetFox; Y"FV#<9@7E  
import java.io.*; $N?8[  
import java.net.*; /k'7j*t Z  
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public class SiteFileFetch extends Thread { \%7*@&  
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SiteInfoBean siteInfoBean = null; //文件信息Bean xpdpD  
long[] nStartPos; //开始位置 ~kW?]/$h  
long[] nEndPos; //结束位置 +tPBm{|  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 <8WFaP3,  
long nFileLength; //文件长度 qzW3MlD  
boolean bFirst = true; //是否第一次取文件 7(@xk_Pl  
boolean bStop = false; //停止标志 yTZev|ej@  
File tmpFile; //文件下载的临时信息 |))NjM'ZBl  
DataOutputStream output; //输出到文件的输出流 'i+L  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） B&cIx~+  
public SiteFileFetch(SiteInfoBean bean) throws IOException r;Sk[Y5#  
{ u=:f%l  
siteInfoBean = bean; :T-DxP/  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); +bumWOQ'  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); }40T'y  
if(tmpFile.exists ()) '| i?-(f)  
{ 0B.Gt&Oal  
bFirst = false; [c{\el9H  
read_nPos(); FL{Uz+Q  
} /A{ Zf'DI  
else x2!R&q8U>  
{ K P]ar.  
nStartPos = new long[bean.getNSplitter()]; U9oUY> 9  
nEndPos = new long[bean.getNSplitter()]; {/QVs?d  
} Lt*P&  
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public void run() P&0eu  
{ dlYpbw}W&<  
//获得文件长度 AE rPd)yk0  
//分割文件 lDL&":t  
//实例FileSplitterFetch `2Pa{g-.  
//启动FileSplitterFetch线程 BqNsW (+  
//等待子线程返回 v@qP &4Sp  
try{ vPDw22L;
'  
if(bFirst) Fi``l)Tt  
{ xF8r+{_J)  
nFileLength = getFileSize(); &M13F>!  
if(nFileLength == -1) V\`Z|'WIQD  
{ W,4
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System.err.println("File Length is not known!"); vT?^#  
} NY7yk3  
else if(nFileLength == -2) ?i _ACKpw  
{ sF{~7IB  
System.err.println("File is not access!"); %,\JTN|g|A  
} yd;e;Bb7*  
else #RlZxtx.O  
{ Q^b&   
for(int i=0;i<nStartPos.length;i++) "D'e  
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); hl1IG !  
} E@GYl85fI  
for(int i=0;i<nEndPos.length-1;i++) "#*W#ohVA  
{ #8Bh5L!SJ1  
nEndPos = nStartPos[i+1]; ?tLApy^`?  
} uSfHlN4l
 
nEndPos[nEndPos.length-1] = nFileLength; !1l~UB_  
}
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} `*s:[k5k  
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//启动子线程 u`'"=Y_E  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; W %*#rcdq  
for(int i=0;i<nStartPos.length;i++) KW:N 6w  
{ B%tF|KKj  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), $7q3[skH  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 4aHogheg  
nStartPos,nEndPos,i); neFwxS?  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); oxxuw Dcl  
fileSplitterFetch.start(); bv4umL /  
} ^L%_kL_7  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), t\,Y<9{w  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); n{gEIUo
#  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", q%sZV>  
nEndPos = " + nFileLength); lE
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// fileSplitterFetch[nPos.length-1].start(); -P
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//等待子线程结束 i.E2a)  
//int count = 0; %axr@o[  
//是否结束while循环 x_Ev2 c'4  
boolean breakWhile = false; Ja6KO2}p  
6*Z7JiQ0  
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while(!bStop) 2F2Hl  
{ DZqPCMz)^  
write_nPos(); k!Yc_ZB:*l  
Utility.sleep(500); cC-8.2  
breakWhile = true; RRja{*R  
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for(int i=0;i<nStartPos.length;i++) ]Q"T8drL  
{ TsFhrtnx&X  
if(!fileSplitterFetch.bDownOver) -lo?16w  
{ 9"P+K.%  
breakWhile = false; M+%Xq0`T  
break; 6 - 3?&+  
} d]0:r]e  
} w;,34qbf  
if(breakWhile) T?RY~GA  
break; m}l);P^  
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27!FB@k-  
//count++; {4S UGo>  
//if(count>4) ~uhW~bT  
// siteStop(); k{2Gq1S{  
} 33~MP;  
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System.err.println("文件下载结束！"); _}5vO$kdO  
} =f~<*wQ  
catch(Exception e){e.printStackTrace ();} I~6) Gk&  
} CQ2vFg3+o  
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//获得文件长度 x'L=p01  
public long getFileSize() 5le
n}){  
{ k7U.]#5V  
int nFileLength = -1; *tv&=  
try{ HR-'8?)R.A  
URL url = new URL(siteInfoBean.getSSiteURL()); nL?P/ \  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Z=&|__+d  
httpConnection.setRequestProperty("User-Agent","NetFox"); [KA^+n  
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int responseCode=httpConnection.getResponseCode(); 1WtE
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if(responseCode>=400) "w?0f["  
{ 54p{J  
processErrorCode(responseCode); Z'i@;^=A  
return -2; //-2 represent access is error :u7BCV|yr  
} =K:[26  
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String sHeader; ^=x/:0  
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for(int i=1;;i++) d}O\:\}y  
{ 2WS*c7Ct  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 
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//Utility.log(in.readLine()); 6)1PDlB  
sHeader=httpConnection.getHeaderFieldKey(i); Q>$B.z  
if(sHeader!=null) 2q[pOT'k  
{ E7O3$B8  
if(sHeader.equals("Content-Length")) fnX[R2KZ  
{ $2W#'_K+  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); syr0|K[  
break; 6'r;6T *  
} {|oWU8.l  
} 2{j$1EdI@-  
else !\#Wq{p>W*  
break; K^!#;,0  
} 0m3hL~0(a  
} y^H5iB[SPL  
catch(IOException e){e.printStackTrace ();} H|aFs.SEQ  
catch(Exception e){e.printStackTrace ();} b"$?(Y  
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Utility.log(nFileLength); .'=S1|_(  
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return nFileLength; p*PzfSLN  
} N~]qQoj,  
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= 9Yfo,F  
//保存下载信息（文件指针位置） fuj9x;8X0  
private void write_nPos() VKPEoy8H  
{ wa,`BAKJ+F  
try{ *w;?&)8%  
output = new DataOutputStream(new FileOutputStream(tmpFile)); S }`f&  
output.writeInt(nStartPos.length); 79 4UY  
for(int i=0;i<nStartPos.length;i++) K1X-<5]{  
{ N&G'i.w/  
// output.writeLong(nPos); D zD5n  
output.writeLong(fileSplitterFetch.nStartPos); .iV=ybMT  
output.writeLong(fileSplitterFetch.nEndPos); <h#7;o  
} o1#3A  
output.close(); rd&d~R6  
} $W|JQ h  
catch(IOException e){e.printStackTrace ();} ,~cK]!:>s  
catch(Exception e){e.printStackTrace ();} 6Mk#) ebM  
} \SmsS^z(]  
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//读取保存的下载信息（文件指针位置） X_'tgP9  
private void read_nPos() I'IFBVhaYn  
{ GDCp@%xW  
try{ ga|<S@u?}  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); %( OP  [  
int nCount = input.readInt(); /\Nc6Z/ L  
nStartPos = new long[nCount]; Vl+UC1M}B>  
nEndPos = new long[nCount]; P]m{\K  
for(int i=0;i<nStartPos.length;i++) hRXnig{;3  
{  @N '_qu  
nStartPos = input.readLong(); ;uAh)|;S#  
nEndPos = input.readLong(); >e;jGk?-  
} / xv5we~  
input.close(); z(c8]Wu#  
} 9wCgJ$te  
catch(IOException e){e.printStackTrace ();} (P?|Bk[  
catch(Exception e){e.printStackTrace ();} \X\< +KU  
} a)W|gx6Y  
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private void processErrorCode(int nErrorCode) * 4J!@w  
{ "tl{HM5u  
System.err.println("Error Code : " + nErrorCode); JjZB!Lg=  
} vFHeGq70j  
`=;}I@]zj)  
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//停止文件下载 U{
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public void siteStop() .pZYPKMaE  
{ >3g`6d  
bStop = true; hAUP#y@:H:  
for(int i=0;i<nStartPos.length;i++) W\j'8^kI9  
fileSplitterFetch.splitterStop();
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} .feB VRg  
} ;m] nl_vg  
//负责部分文件的抓取 W2h*t"5W  
**FileSplitterFetch.java ,(oolx"Xa  
*/ [&~x5l 8\C  
package NetFox; 7}qxWz  
j+'ua=T3  
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import java.io.*; *# <%04f  
import java.net.*; \ P6 !  
[3=Y 9P:  
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public class FileSplitterFetch extends Thread { An>ai N
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b`%u}^B {  
String sURL; //File URL <- sr&  
long nStartPos; //File Snippet Start Position Zl%)#=kO  
long nEndPos; //File Snippet End Position h7ZH/g$)  
int nThreadID; //Thread's ID k
ReZch}  
boolean bDownOver = false; //Downing is over 1d!s8um;  
boolean bStop = false; //Stop identical FLJ&ZU=s  
FileAccessI fileAccessI = null; //File Access interface ~c&sr5E  
|5>A^a  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ,y"vf^BE.  
{ [ {"x{;  
this.sURL = sURL; R%LFFMVn  
this.nStartPos = nStart; :icpPv  
this.nEndPos = nEnd; 7Z+Fjy-B  
nThreadID = id; kqX%y  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 noaR3)  
} MYV3</Xj*  
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public void run() C:&Sk\   
{ wGMoh.GTh  
while(nStartPos < nEndPos && !bStop) >~7XBb08  
{ 3;b)pQ~6CJ  
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try{  e4_A`j'  
URL url = new URL(sURL); IW@xT@  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); *:\[;69[  
httpConnection.setRequestProperty("User-Agent","NetFox"); vS ( Y_6  
String sProperty = "bytes="+nStartPos+"-"; ,;YNI  
httpConnection.setRequestProperty("RANGE",sProperty); V4u4{wU]  
Utility.log(sProperty); rVhfj~Ts  
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InputStream input = httpConnection.getInputStream(); BGVn
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//logResponseHead(httpConnection); GLub5GrxR  
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byte[] b = new byte[1024]; bCTN^  
int nRead; 0gOca +&  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) O|Vc  
{ D\ZH1C!d  
nStartPos += fileAccessI.write(b,0,nRead); (-
1{W^(  
//if(nThreadID == 1) NH5sV.vvc  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); \ eba9i^  
} vnf2Z,f%  
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Utility.log("Thread " + nThreadID + " is over!"); ADxje%!1O  
bDownOver = true; 08AD~^^  
//nPos = fileAccessI.write (b,0,nRead); 2xi;13?  
} 82)=#ye_P  
catch(Exception e){e.printStackTrace ();} X?ZLmP7|  
} US's`Ehx  
} *>2FcoN;  
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V]]!0ugvk(  
//打印回应的头信息 t

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public void logResponseHead(HttpURLConnection con) d/+s-g p  
{ B<myt79F_[  
for(int i=1;;i++) JSq3)o9?/  
{
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String header=con.getHeaderFieldKey(i); E>#@
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if(header!=null) S,|ZCl>+  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); J7dHD(R8  
Utility.log(header+" : "+con.getHeaderField(header)); 8t< X  
else S+Ia2O)BA  
break; ^v5]Aq~X  
} ON{a'H  
} $B9?>a|{A  
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DIP%*b#l$\  
public void splitterStop() s9Tn|Pm+!\  
{ KDf#e3  
bStop = true; v0!(&g3Sd  
} 5D-as9k*  
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} :%28*fl  
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/* VqD_FS;E  
**FileAccess.java f]sR4mhO  
*//文件访问(定位，写) iz[IK%K  
package NetFox; |"b|Q  
import java.io.*; vN]_/T+  
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public class FileAccessI implements Serializable{ #5^OO ou|  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 7N5M=f.DS(  
RandomAccessFile oSavedFile; 2cS94h  
long nPos; TZn5s~t  
2t0VbAO1{  
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public FileAccessI() throws IOException Jv%)UR.]  
{ C>-}BeY!  
this("",0); S,,Wb&A$  
} iB~dO @  
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public FileAccessI(String sName,long nPos) throws IOException sVnq|[ /  
{ W<O/LHKHdn  
oSavedFile = new RandomAccessFile(sName,"rw"); <Vh5`-J  
this.nPos = nPos; <Nloh+n=  
oSavedFile.seek(nPos); vy7?]}MvV  
} wsR\qq  
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public synchronized int write(byte[] b,int nStart,int nLen) vUL@i'0&o  
{ S@ y! 0,  
int n = -1; )Fqtb;W=  
try{ x a\~(B.  
oSavedFile.write(b,nStart,nLen); 23+JuXC6>  
n = nLen; ': Ek3'L  
} VY|UB7,C  
catch(IOException e) n
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{ D4@(_6^  
e.printStackTrace (); uVX,[%*P  
} _S*QIb
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return n; m<;MOS  
} ulEtZ#O{_  
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} f*m^x7  
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/* 6aAN8wO;b  
**SiteInfoBean.java $fPiR  
*/ ]g%HU%R-m  
package NetFox; C.}ho.} r  
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od!s5f!  
public class SiteInfoBean { zQGj,EAM}  
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private String sSiteURL; //Site's URL @P=n{-pIW  
private String sFilePath; //Saved File's Path 6@d/k.3p  
private String sFileName; //Saved File's Name Y'}c$*OkI  
private int nSplitter; //Count of Splited Downloading File :4\_upRE  
]N1,"W}  
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public SiteInfoBean() 11!4#z6w  
{//nSplitter的缺省值为5 K)\D,5X^  
//default value of nSplitter is 5 d(5j#?  
this("","","",5); p-z!i+  
} (f*r  
d%!yFix;<  
L<Z2  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) ?Qpi(Czbpq  
{ %yR80mn8  
sSiteURL= sURL; YR)^F|G  
sFilePath = sPath; :X1Y  
sFileName = sName; #TgP:t]p  
this.nSplitter = nSpiltter; +\vN#xDz  
$ Fy)+<  
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} n@oSLo`k,`  
~(cqFf  
u b@'(
*  
public String getSSiteURL() 0zjGL7  
{ E /ycPqD  
return sSiteURL; CF+:v(NL  
} X`]>J5  
zHW&i~  
)_l(WF.  
public void setSSiteURL(String value) 'E\qqE[;  
{ tK\$LZ  
sSiteURL = value; nxuR^6Ai  
} H_l>L9/\  
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public String getSFilePath() |A H@
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{ \J6e/ G  
return sFilePath; AUaupNN  
} $BOIa  
25;`yB$  
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public void setSFilePath(String value) /\pUA!G)BD  
{ >k2^A  
sFilePath = value; w#sP5qKv8  
} J=#9eW  
t.7_7`bin~  
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public String getSFileName() A&Q!W)=  
{ Ez>!%Hpn\  
return sFileName; sgB|2cj;j  
} l-'\E6grdH  
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d^|r#"o[  
public void setSFileName(String value) L%.=SbmS  
{ XfwH1n/o#  
sFileName = value; A+hT2Ew@t}  
} fp"GdkO#}i  
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x=1Sbs w{  
public int getNSplitter() pzDz@lAwR  
{ ^Ov+n1,)  
return nSplitter; T%2%*oa  
} VmTgD96  
#XAH`L\  
7"{
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public void setNSplitter(int nCount) M[&p[P@  
{ 2AjP2  
nSplitter = nCount; x=44ITe1n[  
} p"NuR4  
} U9//m=_  
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/* l @r`NFWD@  
**Utility.java RgVg~?A@  
*/ '/F~vSQsR  
package NetFox; o@|kq1m8  
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public class Utility { )B Xl|V,  
5R#:ALwX:  
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public Utility() I]N!cEr;@-  
{ '\LU 8VC  
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 bzX/Zts  
} elb}] +  
qo}u(pOj|  
//线程睡眠 l,E4h-$  
public static void sleep(int nSecond) S2 YxA  
{ ']vMOGG  
try{ d|$-l:(J  
Thread.sleep(nSecond); +PHuQ  
} _dn*H-5hO  
catch(Exception e) boIFN;Aq"  
{ q%Lw#f  
e.printStackTrace (); M_F4I$V4  
} DOWZhD  
} Z ,98  
VD2o#.7*eu  
//日志 RS Vt

 
public static void log(String sMsg) sQa9M  
{ )Z@hk]@?_[  
System.err.println(sMsg); Th5}?j7  
} ]\J(  
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?}U l(  
public static void log(int sMsg) eLop}*k  
{ .+CMm5T  
System.err.println(sMsg); >tV:QP]Y  
} 78u=Jz6  
} *(Us:*$W.  
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'J#uD|9)  
/* |>=\ VX17  
**TestMethod.java _zFJ]7Ym.)  
*/ OMN|ea.O  
package NetFox; ~bX ) %jC  
;?!pcvUi  
&ETPYf%#  
public class TestMethod { 8'mm<BV;sT  
;5}y7#4C  
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public TestMethod() I$Fr8R$  
{ ///xx/weblogic60b2_win.exe K|{&SU_m  
try{ q|R$A8)L.  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 4S,/Z{ J.  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); Ya,(J0l  
SiteFileFetch fileFetch = new SiteFileFetch(bean); ^NOy:>  
fileFetch.start(); =zKbvwe%X  
} F
[U0TP@&*  
catch(Exception e){e.printStackTrace ();} <x1H:8A  
)]
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#.~lt8F  
} VufG7%S{  
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public static void main(String[] args) U7Pn $l2!  
{ 8*yky  
new TestMethod(); N!=Q]\ZD  
} 5[>N[}Ck>  
} dZjh@yGP.  
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