http断点续传简单实现（java)

/* weNzYMf%  
**SiteFileFetch.java duX0Mc.0P  
*/ )O,wRd>5  
package NetFox; CF]i}xpWV  
import java.io.*; =%!e(N'p  
import java.net.*; ePf+[pV3  
Dc08D4   
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public class SiteFileFetch extends Thread { LmP qLH'(Q  
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SiteInfoBean siteInfoBean = null; //文件信息Bean ]JOephX2R  
long[] nStartPos; //开始位置 L2KG0i`+  
long[] nEndPos; //结束位置
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 Aj[?aL  
long nFileLength; //文件长度 sU\c#|BSC"  
boolean bFirst = true; //是否第一次取文件 x&'o
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boolean bStop = false; //停止标志 M'kVL0p?vN  
File tmpFile; //文件下载的临时信息 rkkU"l$v  
DataOutputStream output; //输出到文件的输出流 <3d;1o  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） 6yY.!HRkr  
public SiteFileFetch(SiteInfoBean bean) throws IOException i=YXKe6fD  
{ Bd{4Ae\_+g  
siteInfoBean = bean; Ng\/)^  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); C)NC&fV  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); lWW+5  
if(tmpFile.exists ()) *c{wtl@  
{ J^ `hbP+2  
bFirst = false; >ajuk  
read_nPos(); *myG"@P4hW  
} Mtm/}I  
else pe9@N9_5  
{ W4(v6>5l  
nStartPos = new long[bean.getNSplitter()]; sONBQ9  
nEndPos = new long[bean.getNSplitter()]; Bs[nV}c>>  
} wuA
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} MU'@2c  
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public void run() []|;qHhC~(  
{ D3`}4 A  
//获得文件长度 ({4]  
//分割文件 9:5:`'b  
//实例FileSplitterFetch " Ya9~6  
//启动FileSplitterFetch线程 'Gjq/L/x  
//等待子线程返回 Ur^j$B}  
try{ @9Q2$  
if(bFirst) 'B_\TU0 O  
{ p,F^0OU2}:  
nFileLength = getFileSize(); 9IA$z\<<w  
if(nFileLength == -1) %a];  
{ 5!Bktgk.  
System.err.println("File Length is not known!"); $6T3y8  
} n 6{2]&sd  
else if(nFileLength == -2) K$H <}e3  
{ piOXo=9H.  
System.err.println("File is not access!"); BYi)j6"  
} UNDi_6Dy  
else 9GgA6#  
{ q_ %cbAcD  
for(int i=0;i<nStartPos.length;i++) @b2`R3}9R  
{ c8{]]  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); YD\]{,F|  
} *:_P8G;  
for(int i=0;i<nEndPos.length-1;i++) Q/ZkW  
{ +R6a}d/K  
nEndPos = nStartPos[i+1]; n-o3  
} y:d{jG^
 
nEndPos[nEndPos.length-1] = nFileLength; ;gMgj$mI  
} XX6 T$pA6  
} :~zv t  
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//启动子线程 2Vk\L~K  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; F2 ~%zNe  
for(int i=0;i<nStartPos.length;i++) w5KPB5/zu  
{ 
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fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), .R5y:O  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 99=s4*xzM  
nStartPos,nEndPos,i); R^*K6Ad  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos);
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fileSplitterFetch.start(); cu&,J#r%  
} zP!J/}z  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), Z{R[Wx  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); kS :\Oz\  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", %+-C3\'  
nEndPos = " + nFileLength); {f/]5x(_  
// fileSplitterFetch[nPos.length-1].start(); w~Ff%p@9  
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V-!"%fO.s  
//等待子线程结束 YE}s  
//int count = 0; 4=Gph  
//是否结束while循环 w!SkWS b,~  
boolean breakWhile = false; l&$$w!n0w  
@ O>&5gB1u  
8' K0L(3[  
while(!bStop) \}_Yd8  
{ '9?;"=6(  
write_nPos(); uj|BQ`k  
Utility.sleep(500); a%BeqSZh  
breakWhile = true; KCuGu}  
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for(int i=0;i<nStartPos.length;i++) |3hY6aty  
{ 8K9$,Ii  
if(!fileSplitterFetch.bDownOver) 2;`=P5V  
{ T]T;$  
breakWhile = false; }_ mT l@*  
break; E7zm{BX]  
} Bi3+)k>u7  
} ,#]t$mzbQ(  
if(breakWhile) x3pND  
break; ?7MqeR4/E  
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//count++; :_kAl? eJ  
//if(count>4) ]i*](UQ  
// siteStop(); ,`A?!.K$  
}
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System.err.println("文件下载结束！"); p4K.NdUH  
} L,,*gK  
catch(Exception e){e.printStackTrace ();} ]aryV?!6  
} JUAS$Y  
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hsKmnH@#  
//获得文件长度 f~{}zGTM:  
public long getFileSize() cbYLU
\!  
{ Q&'}BeUbm  
int nFileLength = -1; JRMM?y  
try{ 8ho[I]  
URL url = new URL(siteInfoBean.getSSiteURL()); 'b*%ixa  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); US [dkbKo  
httpConnection.setRequestProperty("User-Agent","NetFox"); Gfp1mev  
+;}#B~:  
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int responseCode=httpConnection.getResponseCode(); )~6zYJ2  
if(responseCode>=400) k>jbcSY(z<  
{ _ee dBpV  
processErrorCode(responseCode); $_H`   
return -2; //-2 represent access is error 41a.#o  
} CSPKP#,B0[  
`#-P[q<v-  
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String sHeader; CzCQFqXI  
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for(int i=1;;i++) 4_v]O  
{ {O<l[|Ip  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); C:8_m1Y{  
//Utility.log(in.readLine()); :,b iyJt  
sHeader=httpConnection.getHeaderFieldKey(i); b1XRC`Gy  
if(sHeader!=null) r|e-<t4.9L  
{ .`<@m]m-  
if(sHeader.equals("Content-Length")) SUKxkc(  
{ )Or.;  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); :'F}Dy  
break; klgy;jSEr  
} !+)AeDc:j  
} cRd0S*QN2  
else G$0c'9d*(  
break; 'J&f%kx"  
} v[plT2"s  
} :0)3K7Q  
catch(IOException e){e.printStackTrace ();} {j5e9pg1L|  
catch(Exception e){e.printStackTrace ();} @~c6qh  
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/2EHv.e`  
Utility.log(nFileLength); 1i:|3PA~  
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return nFileLength; *KY=\ %D  
} hQ6a~?f  

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//保存下载信息（文件指针位置） iRg7*MQu  
private void write_nPos() =[\s8XH,  
{ DypFl M*  
try{ %>-@K|:gS  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Uj+j}C  
output.writeInt(nStartPos.length); a22Mufl  
for(int i=0;i<nStartPos.length;i++) b^D$jY  
{ X|0R=n]  
// output.writeLong(nPos); \<}&&SuH  
output.writeLong(fileSplitterFetch.nStartPos); f7h*Vu`>  
output.writeLong(fileSplitterFetch.nEndPos); /!^&;$A'  
} w.,Q1\*rPp  
output.close(); LK6; ?m  
} A;\7|'4  
catch(IOException e){e.printStackTrace ();} P=3RLL<l  
catch(Exception e){e.printStackTrace ();} W^3uEm&l!)  
} %sHF-n5P  
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//读取保存的下载信息（文件指针位置） ?bM_q_5  
private void read_nPos() +xc'1id@[  
{ 7eWk7&Xul  
try{ 9j W2  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); ,rJXy_  
int nCount = input.readInt(); !T]
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nStartPos = new long[nCount]; [,2|Flf e  
nEndPos = new long[nCount]; {hln?'  
for(int i=0;i<nStartPos.length;i++) Ig3;E
+*>  
{ :qChMU|Y6  
nStartPos = input.readLong(); 1]orUF&_  
nEndPos = input.readLong(); 54 >-  
} :Mm3 gW)  
input.close(); z
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} k} ]T;|h]  
catch(IOException e){e.printStackTrace ();} \J+*  
catch(Exception e){e.printStackTrace ();} n,B,"\fw  
} "#(T  
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private void processErrorCode(int nErrorCode) Fu&EhGm6  
{ L\y;LSTU  
System.err.println("Error Code : " + nErrorCode); 6#IU*  
} /axIIfx-  
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//停止文件下载 }%Bl>M
  
public void siteStop()
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{ lA>DS#_  
bStop = true; f!
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for(int i=0;i<nStartPos.length;i++) J'N!Omz  
fileSplitterFetch.splitterStop(); sdQkT#%y  
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} @6l%,N<fou  
} D#&q&6P{  
//负责部分文件的抓取 !"8fdSfg w  
**FileSplitterFetch.java gJ2>(k03y  
*/ lNQcYv  
package NetFox; L%>n>w  
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import java.io.*; lFTF ,G  
import java.net.*; o] mD
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public class FileSplitterFetch extends Thread { YZ%Hu)  
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String sURL; //File URL .BFYY13H  
long nStartPos; //File Snippet Start Position &ZL
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long nEndPos; //File Snippet End Position tK&'<tZh  
int nThreadID; //Thread's ID 5Ri6Z#qm  
boolean bDownOver = false; //Downing is over /z BxJT0  
boolean bStop = false; //Stop identical rXA*NeA3v  
FileAccessI fileAccessI = null; //File Access interface u]vQ>Uu  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException r#xg#uoj  
{ )Tk1 QHU  
this.sURL = sURL; 6;|n]m\Vd  
this.nStartPos = nStart; 9
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this.nEndPos = nEnd; Z!U)I-x&  
nThreadID = id; F'hHK.tT  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 8T(e.I  
} P;k0W>~k  
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public void run() ?.D3'qv  
{ =zyC-;r!  
while(nStartPos < nEndPos && !bStop) 2 !'A:;  
{ n> ^[T[.S  

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try{ {'U Rz[g  
URL url = new URL(sURL); EY \H=@A  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); ;\p KDPr  
httpConnection.setRequestProperty("User-Agent","NetFox"); %'[&U#-  
String sProperty = "bytes="+nStartPos+"-"; 1 5A*7|  
httpConnection.setRequestProperty("RANGE",sProperty); _Gu- uuy  
Utility.log(sProperty); n5{Xj:}  
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1
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InputStream input = httpConnection.getInputStream(); h[PYP5{L  
//logResponseHead(httpConnection); }fKSqB]T-  
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byte[] b = new byte[1024]; {l |E:>Q2  
int nRead; T8^5=/  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) 23h% < ,  
{ 7U"[Gf  
nStartPos += fileAccessI.write(b,0,nRead); ZcaX'5}!S  
//if(nThreadID == 1) 4fe7U=#;Y  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); t*?0D\b 2  
} %JLk$sP9y`  
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Utility.log("Thread " + nThreadID + " is over!"); clk[/'1  
bDownOver = true; ,mj@sC>  
//nPos = fileAccessI.write (b,0,nRead); ~V$|i"  
} \|K;-pL  
catch(Exception e){e.printStackTrace ();} _r2J7&  
} ai{Sa U  
} x:QgjK  
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//打印回应的头信息 uV=Qp1~  
public void logResponseHead(HttpURLConnection con) v'BZs   
{ 9-rNw?7  
for(int i=1;;i++) 0=K9`=5d0  
{ 4n4?4BEn  
String header=con.getHeaderFieldKey(i); hiUD]5Kp  
if(header!=null) 0@EwM  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); qM.bF&&Go  
Utility.log(header+" : "+con.getHeaderField(header)); %DdJ ^qHI  
else kV38`s>+  
break; N2w"R{)j\  
} 0C>%LJ8r  
} 5sb\r,kW  
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public void splitterStop() 8KRba4[  
{ f/V 2f].  
bStop = true; 7P9=)$(EH  
} ldp%{"ZZ  
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} 6qaulwV4t  
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/* 39=1f6I1  
**FileAccess.java :duo#w"K  
*//文件访问(定位，写) =dFv/F/RW  
package NetFox; W]nSR RWco  
import java.io.*; X@f "-\  
$ mI0Bk  
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public class FileAccessI implements Serializable{ ~t~-A,1  
qv@$ZLR  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 ; k)@DX  
RandomAccessFile oSavedFile; 3:C o
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long nPos; *Q,0W:~-  
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public FileAccessI() throws IOException WoBo9aR  
{ =X.9,$Y  
this("",0); M6}3wM*4  
} rW0FA  
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public FileAccessI(String sName,long nPos) throws IOException O
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{ Q_Gi]M9  
oSavedFile = new RandomAccessFile(sName,"rw"); t8dm)s[r8  
this.nPos = nPos; PoT`}-9  
oSavedFile.seek(nPos); QV&D l_  
} 67VT\f  
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public synchronized int write(byte[] b,int nStart,int nLen) xa pq*oj  
{ 1Tm
^  
int n = -1; T16{_  
try{ /,!B2  
oSavedFile.write(b,nStart,nLen); jb^N|zb  
n = nLen; oDU ;E  
} g2T -TG'd  
catch(IOException e) [!U?}1YQ  
{ FG)$y[*  
e.printStackTrace (); l@ap]R  
} oD$J0{K6  
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return n; ,Bal  
} b%S62(qP  
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} QJ7L7S  
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$.[#0lCI  
/* pe{;~-|6  
**SiteInfoBean.java a@0BBihz  
*/ 6%VV,$p  
package NetFox; gw}Mw  
:bC40@  
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public class SiteInfoBean { `2PLWo  
Ed ,D8ND  
4M^G`WA}t9  
private String sSiteURL; //Site's URL 1 %,a =,v  
private String sFilePath; //Saved File's Path b/Xbs0q  
private String sFileName; //Saved File's Name ME=/|.}D<  
private int nSplitter; //Count of Splited Downloading File Vl2XDkhq  
)u
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public SiteInfoBean() V@\%)J'g  
{//nSplitter的缺省值为5 @`,1:
 
//default value of nSplitter is 5 -%I2[)F<   
this("","","",5); B0ndcB-  
} Y]3>7q%  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) iT)z_  
{ T0]*{k(FR  
sSiteURL= sURL; xSBc-u#< G  
sFilePath = sPath; 
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sFileName = sName; dF~8XYo  
this.nSplitter = nSpiltter; >~Qr  
/mK?E5H'r1  
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} 56Vb+0J'  
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public String getSSiteURL() 'gt-s547  
{ I'@Ydt2  
return sSiteURL; Q(\4]i< S  
} IEcf  
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public void setSSiteURL(String value) $]q8, N|1  
{ Bk+{RN(w  
sSiteURL = value; <$hu   
} (k|_J42[  
is@b&V]  
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public String getSFilePath() fks)+L'  
{ bN3#{l-`  
return sFilePath; bl'z<S, '  
} <~)kwq'  
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public void setSFilePath(String value) $/7pYl\n  
{ +Lnsr\BA  
sFilePath = value; ku..aG`  
} D91e\|]  
3q?\r` a  
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public String getSFileName() "hy.GWF|*  
{ rgOfNVyJG<  
return sFileName; STJJU]H  
} 5
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<2nZ&M4/s{  
public void setSFileName(String value) 2 6>ZW4Z  
{ U.@*`Fg  
sFileName = value; ?SC[G-
b  
} Hp(D);0+)  
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public int getNSplitter() EFc-foN  
{ g9Yz*Nee<  
return nSplitter; f +hjC  
} "ax..Mh\y  
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|> _!eS\=<  
public void setNSplitter(int nCount) >pr=|$zk=  
{ dqX;#H}h  
nSplitter = nCount; X~xd/M=9^  
} Jx=hJ-FY  
} 2mq$H_  
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/* ~I(Hc.Q  
**Utility.java 2>l,no39t+  
*/ \t|M-%&)4  
package NetFox; s<]&*e&}?  
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public class Utility { 8j4z{+'TQ  
1c@}C+F+  
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public Utility() Ia'ZV7'  
{ n\ Hs@.  
@p|$/Z%R,  
F]I=+T
 
}
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W k}AmC  
//线程睡眠 X.TI>90{  
public static void sleep(int nSecond) nJbbzQ,e  
{ (S^8UV  
try{ O MX-_\")  
Thread.sleep(nSecond); nL?oTze*p  
} H-p
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catch(Exception e) K)_WL]RJ.4  
{ 9V.u-^o&  
e.printStackTrace (); \`w4|T  
} O$ HBO  
} z7-k`(l4  
2
:LHy[{5  
//日志 O0PJ6:9P  
public static void log(String sMsg) m5D"A D  
{ 9Ok9bC'?8@  
System.err.println(sMsg); J4YBqp  
} vsj3  
RJeSi`19T)  
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public static void log(int sMsg) /(8a~f&%r  
{ Krs2Gre}  
System.err.println(sMsg); 5#E |R  
} x^*1gv $o  
} wl1m*`$  
Yh)Isg|0>  
:L 3&FA  
/* "<i SZ  
**TestMethod.java CD0VfA>Z  
*/ )RsM!}  
package NetFox; Xe+,wW3YF  
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public class TestMethod { LG]3hz9^9  
&5t :H 8b  
-xD*tf*  
public TestMethod() aV1lJ;0  
{ ///xx/weblogic60b2_win.exe %/.a]j!  
try{ ,pBh`av  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); T$=4O9G  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); [\Qr. 2  
SiteFileFetch fileFetch = new SiteFileFetch(bean); pA4*bO+  
fileFetch.start(); ]h9!ei [  
} QjPj[c  
catch(Exception e){e.printStackTrace ();} $t-n'Qh^2  
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#?B%Ja% ;W  
} N:"C+a(  
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public static void main(String[] args)  st'D
 
{ gf)t)-E  
new TestMethod(); j6ut}Uq  
} B%\gkl  
} 5HS~op2n/  
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