http断点续传简单实现（java)

/* Y(U+s\X  
**SiteFileFetch.java ^1 U<,<  
*/ 5JvrQGvL  
package NetFox; ibj3
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import java.io.*;
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import java.net.*; Ho!dtEs  
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public class SiteFileFetch extends Thread { &)Z!A*w]  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 552yzn1  
long[] nStartPos; //开始位置 ipi^sCYp  
long[] nEndPos; //结束位置 _&U.DMt2 C  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 +3wVcL  
long nFileLength; //文件长度 6jaol'{SuH  
boolean bFirst = true; //是否第一次取文件 j~;kh_  
boolean bStop = false; //停止标志 bd& /B&a  
File tmpFile; //文件下载的临时信息 D *Hy 2eZ.  
DataOutputStream output; //输出到文件的输出流 xhTiOt6l  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） W? SFtz  
public SiteFileFetch(SiteInfoBean bean) throws IOException uKF)'gj  
{ 1;FtQnvH  
siteInfoBean = bean; jMUN|(=Y  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); !kG2$/lR  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); $kD;*v=  
if(tmpFile.exists ()) kuI%0)iZn  
{ y7Sey;  
bFirst = false; nMT"Rp  
read_nPos(); L5{DWm~@  
} =bgu2#%Z  
else &CcUr#|  
{ EG;y@\]  
nStartPos = new long[bean.getNSplitter()]; GFX$vn-/F  
nEndPos = new long[bean.getNSplitter()]; A^3M~  
} I/vQP+w O  
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} 7,BULs\g  
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public void run() XhEJF !  
{ +_"AF|  
//获得文件长度 ]ur_G`B  
//分割文件 |9*8u>|RC  
//实例FileSplitterFetch o1^Rx5  
//启动FileSplitterFetch线程 $AyE6j_1gX  
//等待子线程返回 b>]MZhLJe  
try{ X={Z5Xxr"  
if(bFirst) 1Ht&;V  
{ kH|cB!?x  
nFileLength = getFileSize(); [,?5}
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if(nFileLength == -1) XtP5IN\S  
{ E,wOWs*  
System.err.println("File Length is not known!"); ,2MLYW,  
} i[V\RKH*F  
else if(nFileLength == -2) appWq}db  
{ ^0T DaZDLp  
System.err.println("File is not access!"); )/mBq#ZS  
} d")TH3pG  
else A.wuB  
{ yc:y}"  
for(int i=0;i<nStartPos.length;i++) k[<Uxh%  
{ s"-gnW  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); mLb>*xt$b@  
} MIx,#]C&  
for(int i=0;i<nEndPos.length-1;i++) ziXZJ^(FI  
{ Y)*:'&~2e  
nEndPos = nStartPos[i+1]; 6(=>!+xpRr  
} -?}Z0e(w
 
nEndPos[nEndPos.length-1] = nFileLength; T@P[jtH<d  
} k,GAHM"'  
} ww#]i&6  
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//启动子线程 d,+a}eTP'  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; e4mAKB s!  
for(int i=0;i<nStartPos.length;i++) )0UXTyw^  
{ ~M Mv+d88  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), #Et%s8{  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), a]4h5kJ';  
nStartPos,nEndPos,i); 'fS&WVR?  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); <l!{j?Kx  
fileSplitterFetch.start(); XN %tcaY  
} _|f_%S8a_=  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), {$P')>/  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); yO*HJpc
 
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", qS?uMms7w  
nEndPos = " + nFileLength); `E:&a]ul  
// fileSplitterFetch[nPos.length-1].start(); kPvR ,  
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W"[Q=$2<<  
//等待子线程结束 I:=rwnd  
//int count = 0; #C#*yE  
//是否结束while循环 h*B7UzCg  
boolean breakWhile = false; %k=c9ll@:  
2|}`?bY]i`  
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while(!bStop) 8m"(T-wb6{  
{ {\p&?  
write_nPos(); 3!qp+i)?  
Utility.sleep(500); `&w{-om\  
breakWhile = true; rF\L}& Sw  
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{  
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for(int i=0;i<nStartPos.length;i++) :c}"a(|  
{ e754g(|>b  
if(!fileSplitterFetch.bDownOver) O]VHX![Y$  
{ pz0Q@n/X  
breakWhile = false; UB2Ft=  
break; a%XF"
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} eo&^~OVT  
} q.s'z}  
if(breakWhile) IlfH  
break; 9YEE.=]T  
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//count++; >hv8zHOO:  
//if(count>4) *&O4b3R  
// siteStop(); <swfYT!N  
} kK%@cIXS3  
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System.err.println("文件下载结束！"); %}[/lIxaE  
} ln*jakRrC  
catch(Exception e){e.printStackTrace ();} \IX|{]*D  
} PTP0 _|K  
##5e:<c&[  
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//获得文件长度 a%*W( 4=Y  
public long getFileSize() vf0 fa46  
{ |*>s%nF|  
int nFileLength = -1; )z!#8s  
try{ b"pN;v  
URL url = new URL(siteInfoBean.getSSiteURL()); 9r=yfc!cS  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); )Nt'Z*K*  
httpConnection.setRequestProperty("User-Agent","NetFox"); 2OZ<t@\OY  
/K :H2?J  
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int responseCode=httpConnection.getResponseCode(); ,{Ga7rH*   
if(responseCode>=400) vWVQ8S.  
{ M~l\rg8  
processErrorCode(responseCode); 0WQd#l  
return -2; //-2 represent access is error 7 0Wy]8<P  
} 5
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String sHeader; ,buo&DT{L  
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for(int i=1;;i++) AB=Wj*fr  
{ RgSB?  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); 2Kz407|'  
//Utility.log(in.readLine()); .1F41UyL  
sHeader=httpConnection.getHeaderFieldKey(i); WCyjp  
if(sHeader!=null) &Pe[kCO]  
{ R/P9=yvg0  
if(sHeader.equals("Content-Length")) EYR%u'&7'  
{ bltZQI|  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); k2:mIp\  
break; OLE@35"v]  
} iLk"lcX  
} r1a/'+  
else 6QePrf  
break; FV\$M6 _  
} q'KXn0IY#  
} ,% *Jm
  
catch(IOException e){e.printStackTrace ();} I/_,24[  
catch(Exception e){e.printStackTrace ();} F0KNkL>&g  
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Utility.log(nFileLength); /E^j}H{  
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return nFileLength; M5c *vs  
}  U92?e}=]  
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<(_${zR  
//保存下载信息（文件指针位置） Gdv{SCV  
private void write_nPos() QRHM#v S  
{ !l
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try{ T)mh  
output = new DataOutputStream(new FileOutputStream(tmpFile)); * TByAa{  
output.writeInt(nStartPos.length); kb[+II  
for(int i=0;i<nStartPos.length;i++) s)}EMDY  
{ 5"z~
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// output.writeLong(nPos); j$Vtd&  
output.writeLong(fileSplitterFetch.nStartPos); >K*TgG6!X  
output.writeLong(fileSplitterFetch.nEndPos); GB{Q)L  
} , %A2wV  
output.close(); G5*_  
} xM13OoU  
catch(IOException e){e.printStackTrace ();} sfR0wEqI  
catch(Exception e){e.printStackTrace ();} ,lQfsntk'  
} cB_3~=fV  
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//读取保存的下载信息（文件指针位置） e_dsBmTh  
private void read_nPos() Ns6CxE9  
{ \9k{h08s  
try{ t'*2)U  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); /_i]bM7W  
int nCount = input.readInt(); S#l)|c_~  
nStartPos = new long[nCount]; -~_;9[uV  
nEndPos = new long[nCount]; D)bR-a_^  
for(int i=0;i<nStartPos.length;i++) ZU.f)94u  
{ Idr|-s%l6'  
nStartPos = input.readLong(); Qk8YR5K   
nEndPos = input.readLong(); 8_{XrTw(  
} :tp{(MF  
input.close(); Y|L]#  
} 85ND 3F6q4  
catch(IOException e){e.printStackTrace ();} 5](,N^u{):  
catch(Exception e){e.printStackTrace ();} #Kt5+"+7  
} #R#|hw  
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private void processErrorCode(int nErrorCode) M[6WcH0/T  
{ ]?V2L`/  
System.err.println("Error Code : " + nErrorCode); 9`G}GU]@}  
} !uN_<!  
T^H`$;\  
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//停止文件下载 Z(hRwIOF  
public void siteStop() I ka V g L  
{ ]lA.?  
bStop = true; 6B@{X^6y  
for(int i=0;i<nStartPos.length;i++) M3YC@(N% k  
fileSplitterFetch.splitterStop(); 8g6G},Y0  
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} #$v,.Yk  
} o_?A^u  
//负责部分文件的抓取 >qci$  
**FileSplitterFetch.java 6mC% zXR5  
*/ V?4G~~F  
package NetFox; *7K)J8kq  
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import java.io.*; \g:Bg%43h  
import java.net.*; e`;U9Z  
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public class FileSplitterFetch extends Thread { E7j9A`  
!\|L(Paf  
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String sURL; //File URL ]t;bCD6*  
long nStartPos; //File Snippet Start Position bf
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long nEndPos; //File Snippet End Position fe7DS)U  
int nThreadID; //Thread's ID q[TW  
boolean bDownOver = false; //Downing is over 9FmX^t$T  
boolean bStop = false; //Stop identical .h\[7r  
FileAccessI fileAccessI = null; //File Access interface d5 U+]g  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException ,{g B$8z^  
{ ;(;{~1~  
this.sURL = sURL; B/bS:  
this.nStartPos = nStart; z+X DN:  
this.nEndPos = nEnd; C%;J9(r  
nThreadID = id; e18}`<tW-  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 !f*t9 I9Q  
} F
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public void run() A IsXu"  
{ (zhi/>suG  
while(nStartPos < nEndPos && !bStop) u;=a=>05IR  
{ Xv?'*2J  
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try{ uOQl;}Lk5  
URL url = new URL(sURL); I2*\J)|f  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Ui05o7xg~p  
httpConnection.setRequestProperty("User-Agent","NetFox"); ]VHO'z\m  
String sProperty = "bytes="+nStartPos+"-"; .{66q#.  
httpConnection.setRequestProperty("RANGE",sProperty); Ugv"A;l  
Utility.log(sProperty); Lb%:u5X\D@  
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/PgcW  
InputStream input = httpConnection.getInputStream(); @M8vPH  
//logResponseHead(httpConnection); [h~#5x  
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byte[] b = new byte[1024]; #mH4\s  
int nRead; Oh/2$72  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) F@jyTIS^  
{ Oo8"s+G  
nStartPos += fileAccessI.write(b,0,nRead); 4'U #<8  
//if(nThreadID == 1) Wf5ohXm>  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); S'%!KGVe  
} R^tDL  
VT5o#NR{R  
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Utility.log("Thread " + nThreadID + " is over!"); D|X@aUp8}  
bDownOver = true; /|aD,JVN"  
//nPos = fileAccessI.write (b,0,nRead); %$}*y   
} <#No t1R  
catch(Exception e){e.printStackTrace ();} KPB^>,T2{  
} ,|Lf6k  
} 7Un5Y[FZo  
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"CF{Mu|Q
=  
//打印回应的头信息 ,-_\Y hY>  
public void logResponseHead(HttpURLConnection con) /\|Behif  
{ i8>^{GODR  
for(int i=1;;i++) [Z{0|NR  
{ `HJRXoLySW  
String header=con.getHeaderFieldKey(i); 9zD^4j7  
if(header!=null) Sz'JOBp  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); ad'C&^o5  
Utility.log(header+" : "+con.getHeaderField(header)); TaE&8;H#N  
else ~t.M!vk  
break; 7&{[Y^R]"  
} D+69U[P_A  
} 8^av&u$  
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public void splitterStop() V~_aM@q1  
{ Tq`rc"&7u  
bStop = true; !%Qm{R  
} &kNJs{  
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} J:JkX>n%k=  
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/* =r1@?x  
**FileAccess.java 1"P^!N  
*//文件访问(定位，写) c(G;O)ikS  
package NetFox; KiO1l{.s8n  
import java.io.*; *:hHlH* t1  
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public class FileAccessI implements Serializable{ t+@UC+aW  
6
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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 1*ui|fuK  
RandomAccessFile oSavedFile; <zhN7="  
long nPos; C le
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public FileAccessI() throws IOException euc|G Xs  
{ *mTx0sQz(J  
this("",0); 1Wy0#?L  
} UA]U_P$c  
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public FileAccessI(String sName,long nPos) throws IOException y?*4SLy
 
{ MH=;[| N  
oSavedFile = new RandomAccessFile(sName,"rw"); ^i!6q9<{e  
this.nPos = nPos; "~^#{q  
oSavedFile.seek(nPos); -=CZhp  
} O0Sk?uJ<  
^P !}
"  
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public synchronized int write(byte[] b,int nStart,int nLen) u?+i5=N9{  
{ 5$.e5y<&(  
int n = -1; i$:QOMA  
try{ +ZK12D}  
oSavedFile.write(b,nStart,nLen); cas5  
n = nLen; I#U"DwM  
} E ) iEWc  
catch(IOException e) oz[: T3oE>  
{ pa)2TL/@  
e.printStackTrace (); z),@YJU"z  
} 8C(@a[V  
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return n; &q0s8'qA  
} 98x&2(N  
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} Bp>Z?"hTe  
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z.%K5vrO>  
/* ^a+H`RD  
**SiteInfoBean.java sj& j\<(  
*/ C`LHFqv  
package NetFox; F.[E;gOTo  
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public class SiteInfoBean { mxQPOu  
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private String sSiteURL; //Site's URL ,8^QV3  
private String sFilePath; //Saved File's Path ym~  
private String sFileName; //Saved File's Name f7_EqS=(  
private int nSplitter; //Count of Splited Downloading File E+$%88  
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public SiteInfoBean() /3mt=1/~{B  
{//nSplitter的缺省值为5 oPCtLz}z  
//default value of nSplitter is 5 9p{7x[C  
this("","","",5); r{pbUk  
} *t3
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) mv;;0xH  
{ -{ M(1vV(=  
sSiteURL= sURL; N& 683z  
sFilePath = sPath; `C+>PCO  
sFileName = sName; O<KOsu1WW  
this.nSplitter = nSpiltter; fCa*#ME  
}cPH}[$zF  
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} -h?ed'e/zz  
6b6rM%B.oD  
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public String getSSiteURL() )W1tBi  
{ D`e6#1DbJ  
return sSiteURL; 4ZAnq{nR4  
} uKL4cr@  
@j/|U04_Z  
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public void setSSiteURL(String value) vl,Ff9  
{ 3{*nG'@Mal  
sSiteURL = value; Q 
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} 2:4:Q[{A  
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9\J.AAk~/  
public String getSFilePath() <<5x"W(,  
{ LI`H,2Km  
return sFilePath; aR0'$*3E  
} M8p6f)l3  
Y;dQLZCC  
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public void setSFilePath(String value) '1r<g\l  
{ +IkL=/';#  
sFilePath = value; )] C"r_  
} io1hUZ  
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}S_#*N)i  
public String getSFileName() zY^QZceq"  
{ X]T&kdQ6q  
return sFileName; (- QvlpZ  
} 31> $;"  
\lBY4j+;  
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public void setSFileName(String value) e_v_y$  
{ )@,zG(t5;  
sFileName = value; qwomc28O  
} >o_cf*nx  
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public int getNSplitter() &hco3HfW  
{ (aTpBXGr=  
return nSplitter; @}+F4Xh,L  
} Ak'=/`+p  
-D&d1`N4  
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public void setNSplitter(int nCount) qQ T^d  
{ E# UAC2Q  
nSplitter = nCount;
8[\~}Q6  
} ^|j @' @L  
} OB5t+_s  
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/* :% m56  
**Utility.java }xG~a=,  
*/ y|Vwy4tK9  
package NetFox; PC55A1(T  
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public class Utility { EWNm }C9  
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public Utility() mDX UF~G[  
{ *:tfz*FG$G  
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} :|TQi9L$rj  
\{K~x@`  
//线程睡眠 ^9`S`Bhp  
public static void sleep(int nSecond) 9tBE=L=  
{ (D~NW*,9  
try{ $s,A
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Thread.sleep(nSecond); W'3~vQF  
}
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catch(Exception e) t}x^*I$*  
{ mVVL[z2+  
e.printStackTrace (); bb}$7v`G  
} o)r%4YOL  
} >V|KS(}s  
yD:}&!\}  
//日志 t1rAS.z&  
public static void log(String sMsg) + X0db  
{ -hpC8YS  
System.err.println(sMsg); 0Ma3  
} 
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g),t  
public static void log(int sMsg) PGNH<E)  
{ |:)ARH6l#  
System.err.println(sMsg); {T'M4y=)i  
} _<m yM2z  
} yDmx)^En  
''3b[<  
dk[MT'DV  
/* a
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**TestMethod.java "R %3v.Z  
*/ o%_Hmd;_'  
package NetFox; a=&{B'^G  
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public class TestMethod { u81@vEK:_  
e{E8_2d  
nz_1Fu>g|  
public TestMethod() >(BAIjF E\  
{ ///xx/weblogic60b2_win.exe :/~TV   
try{ CEEAyip-c  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); Qf.]Mw?Bm  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); 3#Qek2  
SiteFileFetch fileFetch = new SiteFileFetch(bean); p|RFpn2ygF  
fileFetch.start(); \wM8I-f!  
} fA" VLQE  
catch(Exception e){e.printStackTrace ();} pZV=Co3!I  
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} ZMGthI}~-  
Z,JoxK2"  
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public static void main(String[] args) PCs`aVZ  
{ l,@rB+u
 
new TestMethod(); #Zj3SfU~`  
} .ovG_O  
} 4ZCD@C  
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